阅读说明：本技术 一种车辆的自动换道方法及装置 (Automatic lane changing method and device for vehicle ) 是由 涂强 苏阳 肖志光 梁志远 于 2018-07-12 设计创作，主要内容包括：本申请公开一种车辆的自动换道方法及装置,属于车辆技术领域,包括：处于自动驾驶状态的车辆接收换道请求,预测到达换道终点时车辆的运动状态,为车辆规划第i时刻的换道线路和车速,根据换道线路的曲率、车速和方向盘转角模型确定第i时刻车辆的方向盘转角,若该转角未落入有效的转角范围内,则返回为车辆规划第i时刻的换道线路和车速的步骤,否则,根据车辆运动模型、第i时刻车辆的运动状态和方向盘转角确定第i+1时刻车辆的运动状态,若第i+1时刻车辆的运动状态与预测的运动状态之间的误差大于预设误差,则将i更新为i+1,返回为车辆规划第i时刻的换道线路和车速的步骤；否则,根据规划的各时刻的换道线路和车速驱动车辆进行换道。(The application discloses automatic lane changing method and device of a vehicle, belongs to the technical field of vehicles, and comprises the following steps: the method comprises the steps that a vehicle in an automatic driving state receives a lane changing request, the motion state of the vehicle is predicted when the vehicle reaches a lane changing terminal, a lane changing line and the vehicle speed at the ith moment are planned for the vehicle, the steering wheel angle of the vehicle at the ith moment is determined according to the curvature of the lane changing line, the vehicle speed and a steering wheel angle model, if the steering angle does not fall into an effective steering angle range, the step of planning the lane changing line and the vehicle speed at the ith moment is returned to the vehicle, otherwise, the motion state of the vehicle at the (i + 1) th moment is determined according to the vehicle motion model, the motion state of the vehicle at the ith moment and the steering wheel angle, if the error between the motion state of the vehicle at the (i + 1) th moment and the predicted motion state is larger than the preset error, i is updated to be i +1, and the step of planning the lane; otherwise, driving the vehicle to change the lane according to the planned lane change line and the planned vehicle speed at each moment.)

1. An automatic lane changing method for a vehicle, comprising:

a vehicle in an automatic driving state receives a lane changing request, wherein the lane changing request carries lane changing direction information;

predicting the motion state of the vehicle when reaching a lane change terminal according to the lane change direction information, the collected front image and the current vehicle speed;

planning a lane change line and a vehicle speed at the ith moment for the vehicle, wherein the lane change line and the vehicle speed at the ith moment are obtained by planning with the motion state of the vehicle as an initial motion state and the predicted motion state of the vehicle as a target motion state at the ith moment, and determining a steering wheel angle of the vehicle at the ith moment according to the curvature of the lane change line at the ith moment, the vehicle speed and an established model for determining the steering wheel angle, wherein i is an integer greater than or equal to 0;

judging whether the steering wheel angle of the vehicle at the ith moment falls into an effective steering wheel angle range, wherein the effective steering wheel angle range is determined according to the position of a lane change starting point and the position of a lane change end point, if not, returning to the step of planning a lane change line and the vehicle speed for the vehicle at the ith moment, and if so, determining the motion state of the vehicle at the (i + 1) th moment according to a vehicle motion model, the motion state of the vehicle at the ith moment and the steering wheel angle;

judging whether the error between the motion state of the vehicle and the target motion state at the ith +1 moment is larger than a preset error or not, if so, updating i to be i +1, and returning to the step of planning a lane change line and a vehicle speed at the ith moment for the vehicle; and if not, driving the vehicle to change the lane according to the lane changing route and the vehicle speed at each time planned for the vehicle.

2. The method of claim 1, wherein predicting a state of motion of the vehicle at a lane-change end based on the lane-change direction information, the captured forward image, and a current vehicle speed comprises:

determining a lane on which the vehicle runs after lane changing is finished according to the lane changing direction information;

extracting image information of lane lines on the left side and the right side of the lane from each acquired front image, and determining a mathematical expression of a driving route planned for the vehicle when the vehicle drives along the lane according to the extracted image information of the lane lines on the left side and the right side and relative driving position information in the lane set for the vehicle; and are

Inputting the vehicle speed into a pre-fitted model for determining lane changing distance, and taking the output of the model as the distance required by lane changing;

and determining the motion state of the vehicle when reaching the lane change terminal according to the determined mathematical expression of the driving route and the distance required by the lane change.

3. The method according to claim 2, wherein determining a mathematical expression of a travel route planned for the vehicle while traveling along the lane, based on the extracted image information of the left and right lane lines and the relative travel position information in the lane set for the vehicle, includes:

determining a mathematical expression of each side lane line according to the extracted image information of the side lane line;

and determining a mathematical expression of a driving route planned for the vehicle when driving along the lane according to the mathematical expressions of the lane lines on the left side and the right side and the relative driving position information in the lane set for the vehicle.

4. The method of claim 3, wherein the moving state of the vehicle includes coordinates and a heading angle of the vehicle, and determining the moving state of the vehicle at the time of reaching the lane change end point based on the determined mathematical expression of the travel route and the distance required for the lane change includes:

determining the coordinate of a lane change terminal point according to the mathematical expression of the driving route and the distance required by the lane change;

and solving a first derivative function of the mathematical expression of the running route, calculating the value of the first derivative function at the coordinate, and taking the value as the course angle of the vehicle when the lane change terminal point is reached.

5. The method of claim 4, further comprising:

solving a second derivative function of the mathematical expression of the driving route, calculating a value of the second derivative function at the coordinate, and taking the value as a target curvature of a last section of lane change route planned for the vehicle;

and when determining that the error between the motion state of the vehicle and the target motion state at the (i + 1) th moment is smaller than a preset error, further comprising:

and determining that the error between the curvature of the lane change line planned for the vehicle at the ith moment and the target curvature is smaller than a preset value.

6. The method of claim 1, wherein determining a steering wheel angle of the vehicle at time i based on the curvature of the lane change at time i, the vehicle speed, and an established model for determining the steering wheel angle comprises:

substituting the curvature U and the vehicle speed v of the lane change line at the ith moment into the following formula:

δ_h＝U·(1+K·v²)·L·i_s；

obtaining the steering wheel angle delta of the vehicle at the ith moment_h；

Wherein L is the distance between the front axle and the rear axle of the vehicle, i_sK is a predetermined steering factor for the steering gear ratio of the vehicle.

7. An automatic lane changing device for a vehicle, comprising:

the receiving module is used for receiving a lane changing request by a vehicle in an automatic driving state, wherein the lane changing request carries lane changing direction information;

the prediction module is used for predicting the motion state of the vehicle when the vehicle reaches a lane change terminal point according to the lane change direction information, the collected front image and the current vehicle speed;

the planning module is used for planning a lane change line and a vehicle speed at the ith moment for the vehicle, wherein the lane change line and the vehicle speed at the ith moment are obtained by planning the motion state of the vehicle as an initial motion state and the predicted motion state of the vehicle as a target motion state, the steering wheel angle of the vehicle at the ith moment is determined according to the curvature of the lane change line at the ith moment, the vehicle speed and an established model for determining the steering wheel angle, whether the steering wheel angle of the vehicle at the ith moment falls into an effective steering wheel angle range is judged, the effective steering wheel angle range is determined according to the position of a lane change starting point and the position of a lane change ending point, if not, the step of planning the lane change line and the vehicle speed at the ith moment for the vehicle is returned, and if yes, the step of planning the lane change line and the vehicle speed at the ith moment according to the motion model of the vehicle, the motion state of the vehicle and the steering wheel angle at the ith moment, determining the motion state of the vehicle at the (i + 1) th moment, wherein i is an integer greater than or equal to 0;

the driving module is used for judging whether the error between the motion state of the vehicle and the target motion state at the ith +1 moment is larger than a preset error or not, if yes, updating i to i +1, and returning to the step of planning a lane change line and a vehicle speed at the ith moment for the vehicle; and if not, driving the vehicle to change the lane according to the lane changing route and the vehicle speed at each time planned for the vehicle.

8. The apparatus of claim 7, wherein the prediction module is specific to,

determining a lane on which the vehicle runs after lane changing is finished according to the lane changing direction information;

extracting image information of lane lines on the left side and the right side of the lane from each acquired front image, and determining a mathematical expression of a driving route planned for the vehicle when the vehicle drives along the lane according to the extracted image information of the lane lines on the left side and the right side and relative driving position information in the lane set for the vehicle; and are

Inputting the vehicle speed into a pre-fitted model for determining lane changing distance, and taking the output of the model as the distance required by lane changing;

and determining the motion state of the vehicle when reaching the lane change terminal according to the determined mathematical expression of the driving route and the distance required by the lane change.

9. The apparatus of claim 8, wherein the prediction module is specific to,

determining a mathematical expression of each side lane line according to the extracted image information of the side lane line;

and determining a mathematical expression of a driving route planned for the vehicle when driving along the lane according to the mathematical expressions of the lane lines on the left side and the right side and the relative driving position information in the lane set for the vehicle.

10. The apparatus of claim 9, wherein the state of motion of the vehicle includes coordinates and a heading angle of the vehicle, the prediction module is specifically configured to,

determining the coordinate of a lane change terminal point according to the mathematical expression of the driving route and the distance required by the lane change;

and solving a first derivative function of the mathematical expression of the running route, calculating the value of the first derivative function at the coordinate, and taking the value as the course angle of the vehicle when the lane change terminal point is reached.

11. The apparatus of claim 10,

the prediction module is further configured to solve a second derivative function for the mathematical expression of the driving route, calculate a value of the second derivative function at the coordinate, and use the value as a target curvature of a last lane change route planned for the vehicle;

the driving module is further configured to determine that an error between the curvature of the lane change route planned for the vehicle at the ith moment and the target curvature is smaller than a preset value when it is determined that the error between the motion state of the vehicle and the target motion state at the (i + 1) th moment is smaller than a preset error.

12. The apparatus according to any of claims 7 to 11, wherein the planning module is specifically configured to,

substituting the curvature U and the vehicle speed v of the lane change line at the ith moment into the following formula:

δ_h＝U·(1+K·v²)·L·i_s；

obtaining the steering wheel angle delta of the vehicle at the ith moment_h；

Wherein L is the distance between the front axle and the rear axle of the vehicle, i_sK is a predetermined steering factor for the steering gear ratio of the vehicle.

13. An electronic device, comprising: at least one processor, and a memory communicatively coupled to the at least one processor, wherein:

the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1 to 6.

14. A computer-readable medium having stored thereon computer-executable instructions for performing the method of any one of claims 1 to 6.

Technical Field

The application relates to the technical field of vehicles, in particular to an automatic lane changing method and device for a vehicle.

Background

With the rapid development of automobile technology, the automatic driving technology has great potential in the aspects of travel safety, energy conservation, environmental protection and the like, and as one of the main driving directions of the semi-automatic driving technology, automatic lane changing has become the research focus of various automobile manufacturers.

Disclosure of Invention

The embodiment of the application provides an automatic lane changing method and device for a vehicle, which are used for solving the problem that in the prior art, a lane changing failure is caused by an overlarge steering wheel corner at a certain moment possibly occurring in the automatic lane changing process.

In a first aspect, an automatic lane changing method for a vehicle provided in an embodiment of the present application includes:

a vehicle in an automatic driving state receives a lane changing request, wherein the lane changing request carries lane changing direction information;

predicting the motion state of the vehicle when reaching a lane change terminal according to the lane change direction information, the collected front image and the current vehicle speed;

planning a lane change line and a vehicle speed at the ith moment for the vehicle, wherein the lane change line and the vehicle speed at the ith moment are obtained by planning with the motion state of the vehicle as an initial motion state and the predicted motion state of the vehicle as a target motion state at the ith moment, and determining a steering wheel angle of the vehicle at the ith moment according to the curvature of the lane change line at the ith moment, the vehicle speed and an established model for determining the steering wheel angle, wherein i is an integer greater than or equal to 0;

judging whether the steering wheel angle of the vehicle at the ith moment falls into an effective steering wheel angle range, wherein the effective steering wheel angle range is determined according to the position of a lane change starting point and the position of a lane change end point, if not, returning to the step of planning a lane change line and the vehicle speed for the vehicle at the ith moment, and if so, determining the motion state of the vehicle at the (i + 1) th moment according to a vehicle motion model, the motion state of the vehicle at the ith moment and the steering wheel angle;

judging whether the error between the motion state of the vehicle and the target motion state at the ith +1 moment is larger than a preset error or not, if so, updating i to be i +1, and returning to the step of planning a lane change line and a vehicle speed at the ith moment for the vehicle; and if not, driving the vehicle to change the lane according to the lane changing route and the vehicle speed at each time planned for the vehicle.

By adopting the scheme, the effective steering wheel corner range in the lane changing process can be determined according to the position of the lane changing starting point and the position of the lane changing end point, and the steering wheel corner of the vehicle at each moment in the lane changing process is ensured to fall into the effective steering wheel corner range, so that the situation that the lane cannot be changed due to the fact that the steering wheel corner at a certain moment in the lane changing process is too large can be effectively avoided, and the lane changing success rate is effectively improved.

In a second aspect, an embodiment of the present application provides an automatic lane changing device for a vehicle, including:

the receiving module is used for receiving a lane changing request by a vehicle in an automatic driving state, wherein the lane changing request carries lane changing direction information;

the prediction module is used for predicting the motion state of the vehicle when the vehicle reaches a lane change terminal point according to the lane change direction information, the collected front image and the current vehicle speed;

the planning module is used for planning a lane change line and a vehicle speed at the ith moment for the vehicle, wherein the lane change line and the vehicle speed at the ith moment are obtained by planning the motion state of the vehicle as an initial motion state and the predicted motion state of the vehicle as a target motion state, the steering wheel angle of the vehicle at the ith moment is determined according to the curvature of the lane change line at the ith moment, the vehicle speed and an established model for determining the steering wheel angle, whether the steering wheel angle of the vehicle at the ith moment falls into an effective steering wheel angle range is judged, the effective steering wheel angle range is determined according to the position of a lane change starting point and the position of a lane change ending point, if not, the step of planning the lane change line and the vehicle speed at the ith moment for the vehicle is returned, and if yes, the step of planning the lane change line and the vehicle speed at the ith moment according to the motion model of the vehicle, the motion state of the vehicle and the steering wheel angle at the ith moment, determining the motion state of the vehicle at the (i + 1) th moment, wherein i is an integer greater than or equal to 0;

the driving module is used for judging whether the error between the motion state of the vehicle and the target motion state at the ith +1 moment is larger than a preset error or not, if yes, updating i to i +1, and returning to the step of planning a lane change line and a vehicle speed at the ith moment for the vehicle; and if not, driving the vehicle to change the lane according to the lane changing route and the vehicle speed at each time planned for the vehicle.

In a third aspect, an electronic device provided in an embodiment of the present application includes: at least one processor, and a memory communicatively coupled to the at least one processor, wherein:

the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method for automatically changing lanes of a vehicle as described above.

In a fourth aspect, embodiments of the present application provide a computer-readable medium storing computer-executable instructions for performing the automatic lane changing method for a vehicle.

In addition, for technical effects brought by any one of the design manners in the second aspect to the fourth aspect, reference may be made to technical effects brought by different implementation manners in the first aspect, and details are not described here.

These and other aspects of the present application will be more readily apparent from the following description of the embodiments.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a schematic diagram of an automatic lane change for a vehicle according to an embodiment of the present disclosure;

FIG. 2 is a flowchart of a method for predicting a vehicle movement state when a lane change destination is reached according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a two-degree-of-freedom model of a vehicle according to an embodiment of the present disclosure;

fig. 4 is a schematic diagram of a lane change route planning result provided in the embodiment of the present application;

FIG. 5 is a flowchart of an automatic lane-changing method for a vehicle according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of an electronic device for implementing an automatic lane changing method for a vehicle according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of another electronic device for implementing an automatic lane changing method for a vehicle according to an embodiment of the present application.

Detailed Description

In order to solve the problem that in the prior art, a lane change failure may be caused by an excessively large steering wheel angle at a certain moment in an automatic lane change process, the embodiment of the application provides an automatic lane change method and device for a vehicle.

The preferred embodiments of the present application will be described below with reference to the accompanying drawings of the specification, it should be understood that the preferred embodiments described herein are merely for illustrating and explaining the present application, and are not intended to limit the present application, and that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Referring to fig. 1, fig. 1 shows a schematic diagram of an automatic lane change of a vehicle provided by an embodiment of the present application, and a relative driving position in a lane set for the vehicle in fig. 1 is a lane center, and it is assumed that the vehicle automatically drives along a middle lane all the time. In practical application, in order to know the information of the lane ahead, the vehicles which automatically run can acquire the image of the lane ahead in real time, when lane changing is needed, lane changing direction information, such as lane changing information towards the left or the right, can be sent to the vehicles, and after the vehicles receive a lane changing request, the motion states of the vehicles, such as the coordinates and the course angle of the vehicles, when reaching the lane changing terminal point can be predicted according to the lane changing direction information, the acquired image of the ahead and the current vehicle speed.

Further planning a lane change line and a vehicle speed at the ith moment for the vehicle, wherein the lane change line and the vehicle speed at the ith moment are obtained by planning with the motion state of the vehicle at the ith moment as an initial motion state and the predicted motion state as a target motion state, and determining the steering wheel angle of the vehicle at the ith moment according to the curvature and the vehicle speed of the lane change line at the ith moment and an established model for determining the steering wheel angle, wherein i is an integer greater than or equal to 0;

judging whether the steering wheel angle of the vehicle at the ith moment falls into an effective steering wheel angle range, wherein the effective steering wheel angle range is determined according to the position of a lane change starting point and the position of a lane change end point, if not, returning to the step of planning a lane change line and the vehicle speed for the vehicle at the ith moment, and if so, determining the motion state of the vehicle at the (i + 1) th moment according to a vehicle motion model, the motion state of the vehicle at the ith moment and the steering wheel angle;

judging whether the error between the motion state of the vehicle and the target motion state at the i +1 th moment is larger than a preset error or not, if so, updating i to be i +1, and returning to the step of planning the lane change line and the vehicle speed at the i th moment for the vehicle, namely continuing to plan the lane change line and the vehicle at the next moment; if not, driving the vehicle to change the lane according to the lane changing route and the vehicle speed at each time planned for the vehicle.

In the embodiment of the application, when lane changing is carried out, an effective steering wheel corner range can be determined according to the positions of a lane changing starting point and a lane changing end point, then lane changing lines and the speed are planned for a vehicle periodically, and when the vehicle is ensured to run by the planned lane changing lines and the speed at each time, the steering wheel corners of the vehicle fall in the effective steering wheel corner range, therefore, the situation that lane changing is unsuccessful due to the fact that the steering wheel corners are too large can be avoided, in addition, the smoothness of steering wheel rotation in the lane changing process can be better ensured by utilizing a vehicle motion model to determine the motion state of the vehicle in an iteration mode at each moment, and the user experience is also better.

The above process is described in detail with reference to specific examples.

With reference to fig. 1, assuming that the lane change direction information carried in the lane change request received by the vehicle is a lane change to the left, the motion state of the vehicle when the lane change is finished can be predicted according to the flow shown in fig. 2:

s201: and determining the lane where the vehicle runs after the lane changing is finished according to the lane changing direction information.

S202: and extracting image information of lane lines on the left and right sides of the lane from each acquired front image, and determining a mathematical expression of a driving route planned for the vehicle when driving along the lane according to the extracted image information of the lane lines on the left and right sides and relative driving position information in the lane set for the vehicle.