Intersection following methods, systems, and vehicles based on vehicle trajectory

Abstract

This invention discloses a method, system, and vehicle for vehicle trajectory following at intersections. The method specifically includes the following steps: S1, acquiring real-time images of the area in front of the vehicle, identifying vehicles traveling in the same direction as target vehicles in the images, and fitting the trajectory of the target vehicles; S2, finding the target vehicle's trajectory with the smallest deviation from the current vehicle's trajectory within the target vehicle's trajectory; S3, when lane lines are detected to disappear, identifying the vehicle closest to the current vehicle in the current lane as a pre-following vehicle, and performing follow detection based on the lateral deviation C0′ between the pre-following vehicle's trajectory and the target vehicle's trajectory. If the pre-following vehicle meets the following conditions, it is then designated as the following vehicle. This invention enables automatic vehicle following at intersections, providing guidance for driving at intersections and improving driving safety at intersections.

Description

Technical Field

[0001] This invention belongs to the field of vehicle following technology, and more specifically, this invention relates to an intersection following method, system and vehicle based on vehicle trajectory. Background Technology

[0002] When a vehicle is crossing an intersection, without lane markings or navigation information, it needs to follow the trajectory of the vehicle in front to maintain ADAS lateral control and guide the vehicle into the opposite lane. However, due to complex road conditions, lane markings at both ends of the intersection are often misaligned, there are straight sections and curves at both ends of the intersection, multiple guide lines, and the vehicle in front changing lanes in the middle of the intersection. This causes the vehicle to hesitate in the intersection, unable to determine the driving route, resulting in the steering wheel wobbling from side to side, affecting the driver's experience and creating safety hazards. Summary of the Invention

[0003] This invention provides a vehicle trajectory-based intersection following method that automatically enables vehicles to follow each other at intersections.

[0004] This invention is implemented as follows: a method for intersection following based on vehicle trajectory, the method specifically includes the following steps:

[0005] S1. Real-time acquisition of images in front of the vehicle, identifying vehicles traveling in the same direction in the images as target vehicles, and fitting the motion trajectory of the target vehicles.

[0006] S2. Find the target trajectory that deviates the least from the trajectory of your own vehicle in the trajectory of the target vehicle.

[0007] S3. When the lane line disappears, the vehicle closest to the vehicle in the lane is taken as the pre-following vehicle. Follow detection is performed based on the lateral deviation C0′ between the pre-following vehicle and the target vehicle's trajectory. If the pre-following vehicle meets the following conditions, it is taken as the following vehicle.

[0008] Furthermore, the specific method for fitting the motion trajectory of the target vehicle is as follows:

[0009] Obtain the coordinates of the n trajectory points closest to the current time for each target vehicle, fit the coordinates of the n trajectory points, and obtain the motion trajectory of the corresponding target vehicle.

[0010] Furthermore, the specific method for obtaining the target's motion trajectory is as follows:

[0011] Extract trajectory point sequence I from the trajectory of this vehicle, and extract trajectory point sequence II from the trajectory of each target vehicle. The trajectory points in trajectory point sequence I and trajectory point sequence II have the same vertical coordinate x.

[0012] Based on the vertical coordinate x, the corresponding trajectory point weights are set, and the lateral weighted deviation Δy of each trajectory point sequence II is calculated. sum ;

[0013] Minimum value Δy sum The corresponding trajectory is the target trajectory.

[0014] Furthermore, the lateral weighted bias Δy sum The specific calculation method is as follows:

[0015]

[0016] Δy[i]=w[i]×|y obj [i]-y hvt [i]|;

[0017] Where Δy[i] represents the lateral weighted deviation of the i-th trajectory point, Δy sum y represents the lateral weighted deviation of the corresponding trajectory point sequence II. obj [i] represents the horizontal coordinate of the i-th trajectory point in trajectory point sequence I, y hvt [i] represents the horizontal coordinate of the i-th trajectory point in the corresponding trajectory point sequence II, and w[i] represents the weight value of the i-th vertical coordinate.

[0018] Furthermore, the larger the value of the vertical coordinate x, the smaller its weight value.

[0019] Furthermore, the specific method for calculating the lateral deviation C0′ between the trajectory of the vehicle to be followed and the target vehicle is as follows:

[0020] Get the coordinates (x, y) of the current position of the vehicle to be followed. cipv ,y cipv ), the vertical coordinate x cipv Input the target's motion trajectory and obtain the longitudinal aiming value. The lateral deviation between the trajectory of the vehicle to be followed and the trajectory of the target vehicle.

[0021] Furthermore, after the motion trajectory is determined to be the target motion trajectory, the target vehicle corresponding to the target motion trajectory is marked.

[0022] If the vehicle to be followed does not meet the following conditions, check whether all target vehicles are marked. If the detection result is no, proceed to step S2.

[0023] Furthermore, the specific conditions are as follows:

[0024] (1) The lateral deviation C0′ is less than the lateral deviation threshold;

[0025] (2) The yaw angle C1 is less than the yaw angle threshold;

[0026] (3) Half curvature C2 is less than the curvature threshold;

[0027] If the vehicle to be followed meets the above three conditions, then the vehicle to be followed meets the following conditions; otherwise, the vehicle to be followed does not meet the following conditions.

[0028] This invention is implemented as follows: an intersection following system based on vehicle trajectory, the system comprising:

[0029] A camera mounted on the vehicle, and a processor that communicates with the camera;

[0030] The camera captures images of the front of the vehicle and sends them to the processor, which then selects the vehicle to follow based on the aforementioned vehicle trajectory-based intersection following method.

[0031] The present invention is implemented as follows: a vehicle that integrates the above-mentioned intersection following system based on vehicle trajectory.

[0032] This invention enables vehicles to automatically follow each other at intersections, providing guidance for driving at intersections and improving driving safety at intersections. Attached Figure Description

[0033] Figure 1 A flowchart of an intersection following method based on vehicle trajectory provided in an embodiment of the present invention. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0035] Figure 1 The flowchart of the intersection following method based on vehicle trajectory provided in the embodiment of the present invention includes the following steps:

[0036] S1. Real-time acquisition of images of the area in front of the vehicle, identifying vehicles traveling in the same direction as the target vehicle in the images, and fitting the trajectory of the target vehicle.

[0037] During the vehicle's journey, images of the area in front of the vehicle are captured in real time. Vehicles in the images are extracted, and vehicles traveling in the same direction as the vehicle are marked. The marked vehicles are the target vehicles.

[0038] The vehicle coordinate system defined in this embodiment of the invention has the rear axle center of the vehicle as the origin, the vehicle's driving direction (i.e., longitudinal) as the x-axis, and the vehicle's width direction (i.e., the lane arrangement direction (lateral)) as the y-axis. During the vehicle's movement, the coordinates (x, y) of the target vehicle in the vehicle coordinate system are acquired in real time. The specific method for fitting the target vehicle's motion trajectory is as follows:

[0039] Obtain the n sets of trajectory coordinates (x, y) of the target vehicle that are closest to the current time. Fit the n sets of trajectory coordinates (x, y) to obtain the motion trajectory of the corresponding target vehicle. The motion trajectory model is as follows:

[0040] y = C0 + C1 × x + C2 × x 2 +C3×x 3

[0041] Where C0, C1, C2, and C3 represent the fitting coefficients.

[0042] S2. Among the unmarked target vehicles, find the target trajectory with the smallest lateral deviation from the trajectory of this vehicle, and mark the target vehicle corresponding to the target trajectory among the target vehicles;

[0043] In this embodiment of the invention, the method for determining the target motion trajectory is as follows:

[0044] The sequence of trajectory points extracted from the trajectory of this vehicle is called trajectory point sequence I. The sequence of trajectory points extracted from the trajectory of each target vehicle is called trajectory point sequence II. The trajectory points in trajectory point sequence I and trajectory point sequence II have the same vertical coordinate x.

[0045] In this embodiment of the invention, the longitudinal coordinate x is taken at set intervals within a set longitudinal distance. For example, if the set longitudinal distance is 50 meters and the set interval is 5 meters, then the longitudinal coordinate array of trajectory point sequence I and trajectory point sequence II is x = [5, 10, 15, 20, 25, 30, 35, 40, 45, 50], and its weight sequence is w = [1, 0.97, 0.95, 0.91, 0.87, 0.81, 0.75, 0.67, 0.59, 0.51].

[0046] The weights of the corresponding trajectory points are set based on the vertical coordinate x. The larger the value of the vertical coordinate x, the farther the corresponding target vehicle is from the current vehicle. Therefore, the smaller its weight value is. The lateral weighted deviation of each trajectory point sequence II is calculated, and the specific calculation method is as follows:

[0047] Δy[i]=w[i]×|yo bj [i]-y hvt [i]|;

[0048]

[0049] Where Δy[i] represents the lateral weighted deviation of the i-th trajectory point, Δy sum y represents the lateral weighted deviation of the corresponding trajectory point sequence II. obj [i] represents the horizontal coordinate of the i-th trajectory point in trajectory point sequence I, yhvt [i] represents the horizontal coordinate of the i-th trajectory point in the corresponding trajectory point sequence II, and w[i] represents the weight value of the i-th vertical coordinate.

[0050] Minimum value Δy sum The corresponding trajectory is the target trajectory.

[0051] S3. When the lane line disappears, the vehicle closest to the vehicle in the lane is taken as the pre-following vehicle. Follow detection is performed based on the lateral deviation C0′ between the pre-following vehicle and the target vehicle's trajectory. If the pre-following vehicle meets the following conditions, it is taken as the following vehicle.

[0052] In this embodiment of the invention, the method for calculating the lateral deviation C0′ between the trajectory of the pre-following vehicle and the target vehicle is as follows:

[0053] Based on the camera-based target selection algorithm (also known as CIPV object selection, where CIPV is short for closestin-path vehicle), the system obtains the nearest vehicle in the current lane (i.e., the vehicle to be followed) and the coordinates (x, y) of the current position of the vehicle to be followed. cipv ,y cipv ), the vertical coordinate x cipv Input the target's motion trajectory and obtain the longitudinal aiming value. The lateral deviation between the trajectory of the following vehicle and the trajectory of the target vehicle.

[0054] The system checks whether the vehicle to be followed meets the following conditions. If the result is yes, the vehicle to be followed is used as the following vehicle. If the result is no, the system checks whether all target vehicles are marked. If the result is no, step S2 is executed. If the result is yes, the system cannot follow the vehicle in front across the intersection and exits the following function.

[0055] In this embodiment of the invention, the following specific conditions are as follows:

[0056] (1) The lateral deviation C0′ is less than the lateral deviation threshold, for example, 3m;

[0057] (2) The yaw angle C1 is less than the yaw angle threshold, for example, 0.26 rad;

[0058] (3) Half curvature C2 is less than the curvature threshold, for example, 0.002 1 / m.

[0059] If the vehicle to be followed meets the above three conditions, then the vehicle to be followed meets the following conditions; otherwise, the vehicle to be followed does not meet the following conditions.

[0060] The present invention also provides an intersection following system based on vehicle trajectory, the system comprising:

[0061] A camera is installed on the vehicle, and a processor is connected to the camera. The camera captures images of the front of the vehicle and sends them to the processor. The processor selects the vehicle to follow based on the aforementioned vehicle trajectory-based intersection following method.

[0062] The present invention also provides a vehicle that integrates the above-mentioned intersection following system based on vehicle trajectory.

[0063] The present invention has been described by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for intersection following based on vehicle trajectory, characterized in that, The method specifically includes the following steps: S1. Real-time acquisition of images in front of the vehicle, using vehicles traveling in the same direction in the images as target vehicles, and fitting the motion trajectory of the target vehicles. S2. Find the target trajectory that deviates the least from the trajectory of your own vehicle in the trajectory of the target vehicle. S3. When the lane line disappears, the vehicle closest to the vehicle in the lane is taken as the pre-following vehicle. Follow detection is performed based on the lateral deviation C0′ between the pre-following vehicle and the target vehicle's trajectory. If the pre-following vehicle meets the following conditions, it is taken as the following vehicle. The specific method for calculating the lateral deviation C0′ between the trajectory of the vehicle to be followed and the target vehicle is as follows: Get the coordinates (x, y) of the current position of the vehicle to be followed. cipv ,y cipv ), and the vertical coordinate x cipv Input the target's motion trajectory and obtain the longitudinal aiming value. The lateral deviation between the trajectory of the vehicle to be followed and the trajectory of the target vehicle.

2. The intersection following method based on vehicle trajectory as described in claim 1, characterized in that, The specific method for fitting the motion trajectory of the target vehicle is as follows: Obtain the coordinates of the n trajectory points closest to the current time for each target vehicle, fit the coordinates of the n trajectory points, and obtain the motion trajectory of the corresponding target vehicle.

3. The intersection following method based on vehicle trajectory as described in claim 1, characterized in that, The specific method for obtaining the target's motion trajectory is as follows: Extract trajectory point sequence I from the trajectory of this vehicle, and extract trajectory point sequence II from the trajectory of each target vehicle. The trajectory points in trajectory point sequence I and trajectory point sequence II have the same vertical coordinate x. Based on the vertical coordinate x, the corresponding trajectory point weights are set, and the lateral weighted deviation Δy of each trajectory point sequence II is calculated. sum ; Minimum value Δy sum The corresponding trajectory is the target trajectory.

4. The intersection following method based on vehicle trajectory as described in claim 3, characterized in that, Lateral weighted deviation Δy sum The specific calculation method is as follows: Δy[i]=w[i]×|y obj [i]-y hvt [i]|; Where Δy[i] represents the lateral weighted deviation of the i-th trajectory point, Δy sum y represents the lateral weighted deviation of the corresponding trajectory point sequence II. obj [i] represents the horizontal coordinate of the i-th trajectory point in trajectory point sequence I, y hvt [i] represents the horizontal coordinate of the i-th trajectory point in the corresponding trajectory point sequence II, and w]i] represents the weight value of the i-th vertical coordinate.

5. The intersection following method based on vehicle trajectory as described in claim 4, characterized in that, The larger the value of the vertical coordinate x, the smaller its weight value.

6. The intersection following method based on vehicle trajectory as described in claim 1, characterized in that, After the motion trajectory is determined to be the target motion trajectory, the target vehicle corresponding to the target motion trajectory is marked. If the vehicle to be followed does not meet the following conditions, check whether all target vehicles are marked. If the detection result is no, proceed to step S2.

7. The intersection following method based on vehicle trajectory as described in claim 1 or 6, characterized in that, The specific conditions for following are as follows: (1) The lateral deviation C0′ is less than the lateral deviation threshold; (2) The yaw angle C1 is less than the yaw angle threshold; (3) Half curvature C2 is less than the curvature threshold; If the vehicle to be followed meets the above three conditions, then the vehicle to be followed meets the following conditions; otherwise, the vehicle to be followed does not meet the following conditions.

8. A vehicle trajectory-based intersection following system, characterized in that, The system includes: A camera mounted on a vehicle, and a processor that communicates with the camera; The camera captures an image of the front of the vehicle and sends it to the processor, which selects a vehicle to follow based on the vehicle trajectory-based intersection following method described in any one of claims 1 to 7.

9. A vehicle, characterized in that, The vehicle is equipped with the intersection following system based on vehicle trajectory as described in claim 8.

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