Lateral control method and apparatus for vehicle

Abstract

The invention relates to a lateral control method of a vehicle. The method includes: determining a curve-related curvature and a curvature change based on a signal received from a sensor; when the curvature and / or the curvature change are / is larger than a preset threshold value, a compensation factor is determined according to the curvature and the vehicle speed, and the compensation factor is used for compensating the influence of the slip angle on the predicted transverse distance; and performing lateral control on the vehicle based on the compensation factor. The invention further relates to a lateral control device of the vehicle, a computer readable storage medium, a computer program product, a vehicle motion controller VMC and the vehicle.

Description

Technical Field

[0001] The present application relates to the field of lateral control of a vehicle, and more specifically, to a lateral control method and device for a vehicle, a computer-readable storage medium, a computer program product, a vehicle motion controller VMC, and a vehicle. Background Art

[0002] Good lateral control performance of a vehicle depends on several factors, among which the lateral distance of the vehicle to the (left and right) lane lines and the (planned) trajectory is a very important factor because it will directly affect the lateral control performance.

[0003] The existing lateral control scheme can maintain good control performance under normal road conditions, but in some extreme situations (such as "sharp bends"), due to the limitations of the vehicle chassis and EPS (electronic power steering system) performance, the lateral control performance is not satisfactory to customers. For example, in some extreme situations, the steering wheel may vibrate, the vehicle may run out of the lane, and the vehicle may run in an S-shaped trajectory within the lane, affecting the driving experience and safety. Summary of the invention

[0004] The inventor of this application proposes to analyze and evaluate the influence of the slip angle on the accuracy of the predicted lateral distance in certain extreme situations (such as "sharp bend" roads), thereby improving the accuracy of the predicted lateral distance from the vehicle to the left or right lane line, or from the vehicle to the planned driving trajectory (taking slip angle compensation into account when calculating the predicted lateral distance). As the accuracy of the predicted lateral distance is improved, the lateral control performance will also be better and better.

[0005] According to one aspect of the present application, a method for lateral control of a vehicle is provided, the method comprising: determining a curvature and a curvature change associated with a curve based on a signal received from a sensor; when the curvature and / or the curvature change is greater than a preset threshold, determining a compensation factor based on the curvature and the vehicle speed, the compensation factor being used to compensate for an effect of a slip angle on a predicted lateral distance; and performing laterally controlling the vehicle based on the compensation factor.

[0006] As a supplement or alternative to the above solution, in the above method, the compensation factor is obtained from a two-dimensional lookup table based on the curvature and the vehicle speed.

[0007] As a supplement or alternative to the above-mentioned scheme, in the above-mentioned method, performing lateral control of the vehicle based on the compensation factor includes: calculating the predicted lateral distance DLC of the vehicle to the left / right lane line or the planned driving trajectory based on the compensation factor; and performing lateral control based on the predicted lateral distance DLC.

[0008] As a supplement or alternative to the above solution, in the above method, the predicted lateral distance DLC is determined according to the following formula:

[0009]

[0010] Among them, c0 is a constant, which represents the lateral offset when the predicted longitudinal distance x=0; c1 represents the offset related to the heading angle θ of the vehicle, which is equal to tan(θ); factor is the compensation factor; c2 represents the curvature; and c3 represents the curvature change.

[0011] According to another aspect of the present application, a lateral control device for a vehicle is provided, the device comprising: a first determination device for determining a curvature and a curvature change associated with a curve based on a signal received from a sensor; a second determination device for determining a compensation factor based on the curvature and the vehicle speed when the curvature and / or the curvature change is greater than a preset threshold, the compensation factor being used to compensate for the influence of the slip angle on the predicted lateral distance; and a control device for performing laterally control of the vehicle based on the compensation factor.

[0012] As a supplement or alternative to the above-mentioned scheme, the above-mentioned device may also include: a switching device for enabling a two-dimensional lookup table when the curvature and / or the curvature change is greater than a preset threshold, so that the second determination device can obtain the compensation factor from the two-dimensional lookup table based on the curvature and the vehicle speed, and the compensation factor is adjustable.

[0013] As a supplement or alternative to the above-mentioned scheme, in the above-mentioned device, the control device includes: a calculation unit, used to calculate the predicted lateral distance DLC of the vehicle to the left / right lane line or the planned driving trajectory based on the compensation factor; and a lateral control unit, used to perform lateral control based on the predicted lateral distance DLC.

[0014] As a supplement or alternative to the above solution, in the above device, the calculation unit determines the predicted lateral distance DLC according to the following formula:

[0015]

[0016] Among them, c0 is a constant, which represents the lateral offset when the predicted longitudinal distance x=0; c1 represents the offset related to the heading angle θ of the vehicle, which is equal to tan(θ); factor is the compensation factor; c2 represents the curvature; and c3 represents the curvature change.

[0017] According to another aspect of the present application, a computer-readable storage medium is provided, wherein the medium includes instructions, and the instructions execute the above method when executed.

[0018] According to another aspect of the present application, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the method described above is implemented.

[0019] According to yet another aspect of the present application, a vehicle motion controller VMC is provided, wherein the vehicle motion controller VMC includes the lateral control device as described above.

[0020] According to another aspect of the present application, a vehicle is provided, comprising: a sensor; and a vehicle motion controller VMC as described above, wherein the vehicle motion controller VMC is configured to receive sensor signals from the sensor so as to perform trajectory planning and control on the vehicle.

[0021] The lateral control scheme of the embodiment of the present application considers the influence of the slip angle on the predicted lateral distance by determining a (slip angle related) compensation factor according to the curvature and vehicle speed when the curvature and / or curvature change related to the curve is greater than a preset threshold value (i.e., indicating that the vehicle may have a "slip angle" in the current curve); and finally controls the vehicle laterally based on the compensation factor. The above-mentioned lateral control scheme can advantageously compensate for the inaccurate part of the predicted lateral distance caused by the possible misalignment between the vehicle's orientation and the vehicle's moving direction, especially for "sharp bend" road scenes. In one embodiment, a switch device is added to enable or disable a two-dimensional lookup table to select whether to use slip angle compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects and advantages of the present application will become more fully apparent from the following detailed description in conjunction with the accompanying drawings, wherein the same or similar elements are represented by the same reference numerals.

[0023] Figure 1 A schematic flow chart of a lateral control method for a vehicle according to an embodiment of the present application is shown;

[0024] Figure 2 A schematic structural diagram of a lateral control device for a vehicle according to an embodiment of the present application is shown;

[0025] Figure 3 A schematic diagram showing calculation of a predicted lateral distance (taking slip angle compensation into account) according to an embodiment of the present application is shown; and

[0026] Figure 4 A schematic diagram showing the calculation of the predicted lateral distance using a simplified model without considering slip angle compensation is shown. DETAILED DESCRIPTION

[0027] Hereinafter, a lateral control scheme of a vehicle according to various exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0028] Figure 1 FIG. 1 is a flow chart of a vehicle lateral control method 1000 according to an embodiment of the present application. Figure 1 As shown, the lateral control method 1000 of a vehicle includes:

[0029] In step S110, the curvature and curvature change associated with the curve are determined based on the signal received from the sensor;

[0030] In step S120, when the curvature and / or the curvature change is greater than a preset threshold, a compensation factor is determined according to the curvature and the vehicle speed, the compensation factor being used to compensate for the influence of the slip angle on the predicted lateral distance; and

[0031] In step S130 , the vehicle is laterally controlled based on the compensation factor.

[0032] Lane detection is a core task in modern assisted and automated driving systems, which can locate the exact shape of each lane in a traffic scene. Compared with straight lanes, the detection of curved lanes (i.e. "bends") is more critical for further downstream trajectory planning tasks, so that the vehicle can maintain the correct positioning with the road lane when turning in complex road scenes.

[0033] In the context of this application, the term "predicted lateral distance" refers to the lateral distance of the vehicle at the predicted distance ahead (i.e., predicted longitudinal distance) relative to the left / right lane line or the planned driving trajectory. The accuracy of the predicted lateral distance will affect the performance of lateral control.

[0034] In step S110, the curvature and curvature change associated with the curve are determined based on the signal received from the sensor. In one embodiment, step S110 includes: receiving signals associated with the left and right lane lines of the curve from a video camera sensor with a preprocessing function; and determining the curvature (curvature) and curvature change (curvature change) of the lane centerline based on the signals associated with the left and right lane lines. The video camera sensor is, for example, a multi-function camera MPC3, which is installed above the rearview mirror of the vehicle and can clearly monitor the road conditions ahead. In particular, MPC3 combines a multi-path recognition algorithm and artificial intelligence for target recognition, making the results of the perception of the surrounding environment more accurate and reliable, thereby improving road traffic safety.

[0035] For a general curve, each point can be approximated as a small arc. After fixing a point, the reciprocal of the radius of the osculating arc at that point is defined as the curvature of the curve at that point. Therefore, the larger the radius of the osculating arc, the smaller the curvature of the curve, and the closer it is to a straight line. So, the larger the radius of curvature, the smaller the curvature, and vice versa. For a curve, the curvature and / or the change in curvature can be used to determine whether the curve is a "sharp curve" (the vehicle may have a slip angle in the current curve).

[0036] In step S120, when the curvature and / or the curvature change is greater than a preset threshold, a compensation factor is determined based on the curvature and the vehicle speed, and the compensation factor is used to compensate for the influence of the slip angle on the predicted lateral distance. When the curve-related curvature and / or the curvature change is greater than a preset threshold (i.e., the vehicle orientation and the vehicle movement direction may be inconsistent in the current curve, i.e., there is a "slip angle"), a compensation factor is determined based on the curvature and the vehicle speed, thereby compensating for the influence of the slip angle on the predicted lateral distance. In other words, the compensation factor Factor is a function of the curvature and the vehicle speed. In one embodiment, the compensation factor is obtained from a two-dimensional lookup table based on the curvature and the vehicle speed. The two-dimensional lookup table may be, for example, as shown in the following table.

[0037]

[0038] In one embodiment, the two-dimensional lookup table may be calibrated in advance by using a test vehicle equipped with GPS to measure the lateral distance in a test field.

[0039] In step S130, the vehicle is laterally controlled based on the compensation factor. In one embodiment, step S130 includes: calculating a predicted lateral distance DLC of the vehicle to a left / right lane line or a planned driving trajectory based on the compensation factor; and performing lateral control based on the predicted lateral distance DLC.

[0040] refer to Figure 4 , which shows a schematic diagram of calculating the predicted lateral distance using a simplified model without considering slip angle compensation. Figure 4 As shown, vehicle 410 is traveling on curve 420 , wherein a left lane line (left boundary) of curve 420 is indicated by 422 , and a right lane line (right boundary) of curve 420 is indicated by 424 .

[0041] Continue to refer Figure 4 In the vehicle coordinate system XY, the X axis is parallel to the ground and points to the front of the vehicle, and the Y axis points to the left of the driver. In this simplified model, it is assumed that the direction of the vehicle is consistent with the direction of the vehicle's speed, so there is no need to consider slip angle compensation. Figure 4In the simplified model shown, the predicted lateral distance DLC in front of the vehicle 410 is equal to L1+L2+L3, where L2 is equivalent to c0, L3 is equivalent to c1*x, where x represents the predicted longitudinal distance, c0 is a constant, representing the lateral offset when the predicted longitudinal distance x=0; c1 represents the heading angle with the vehicle ( Figure 4 α) is shown in FIG, which is equal to tan(α); c2 represents the curvature; and c3 represents the change in curvature.

[0042] It can be seen that due to Figure 4 The influence of the slip angle on the predicted lateral distance is not considered. This has little effect on some not-too-sharp curves (e.g., the curvature or curvature change is less than a predetermined threshold), because the error can be solved by PID control. However, for some extreme cases (e.g., the curvature or curvature change is greater than a predetermined threshold), the error may have a serious impact.

[0043] Figure 3 FIG. 2 shows a schematic diagram of calculating a predicted lateral distance (taking slip angle compensation into account) according to an embodiment of the present application. Figure 3 As shown, the vehicle 310 is traveling in a lane defined by a left lane line (left boundary) 322 and a right lane line (right boundary) 324. Figure 4 Different from the above, there is a slip angle β between the X axis of the vehicle coordinate system and the moving direction of the vehicle (i.e., the direction of speed V), and the lateral distance corresponding to the slip angle β is L4. Therefore, the predicted lateral distance DLC in front of the vehicle 310 is equal to L1+L2+L3+L4 (rather than Figure 3 L1+L2+L3 in the lane boundary coordinate system (also called the lane fixed coordinate system) where L1 represents the lateral distance between the X' axis of the lane boundary coordinate system (also called the lane fixed coordinate system) and the left lane line 322, L2 represents the lateral distance from the vehicle to the left lane line 322 in the lane boundary coordinate system X'Y', L3 represents the lateral distance corresponding to the heading angle α, and L4 represents the lateral distance corresponding to the slip angle β. Figure 4 As shown, L4 can be calculated by the following formula: d(pred)*tan(α+β)-d(pred)*tan(α), where d(pred) represents the predicted longitudinal distance in front of the vehicle in the lane boundary coordinate system.

[0044] Therefore, theoretically, as long as L4 of each curve is known, a relatively accurate predicted lateral distance DLC can be obtained. However, for the slip angle β, it is generally difficult to know its exact value. Therefore, after considering factors such as complexity and implementation cost, the inventor of the present application proposes a compensation factor (coefficient), wherein the compensation factor is used to compensate the predicted lateral distance corresponding to the slip angle β.

[0045] In one embodiment, the predicted lateral distance DLC is determined according to the following formula:

[0046]

[0047] Wherein, c0 is a constant, representing the lateral offset when the predicted longitudinal distance x=0; c1 represents the offset related to the heading angle α of the vehicle, which is equal to tan(α); factor is the compensation factor; c2 represents the curvature; and c3 represents the curvature change. In other words, L2 is equivalent to c0, L3+L4 is equivalent to c1*x*factor, where the value of the compensation factor is greater than 1, and x represents the predicted distance in front of the vehicle (predicted longitudinal distance) in the lane boundary coordinate system.

[0048] In addition, it is easy for a person skilled in the art to understand that the lateral control method 1000 of a vehicle provided in the above one or more embodiments of the present application can be implemented by a computer program. For example, the computer program is included in a computer program product, and when the computer program is executed by a processor, the lateral control method 1000 of a vehicle in one or more embodiments of the present application is implemented. For another example, when a computer-readable storage medium (such as a USB flash drive) storing the computer program is connected to a computer, the lateral control method 1000 of a vehicle in one or more embodiments of the present application can be executed by running the computer program.

[0049] refer to Figure 2 , Figure 2 The schematic diagram of the structure of a lateral control device 2000 of a vehicle according to an embodiment of the present application is shown. The lateral control device 2000 comprises: a first determining device 210, a second determining device 220 and a control device 230, wherein the first determining device 210 is used to determine the curvature and curvature change related to the curve based on the signal received from the sensor; the second determining device 220 is used to determine the compensation factor according to the curvature and the vehicle speed when the curvature and / or the curvature change is greater than a preset threshold, and the compensation factor is used to compensate for the influence of the slip angle on the predicted lateral distance; and the control device 230 is used to perform lateral control on the vehicle based on the compensation factor.

[0050] Lane detection is a core task in modern assisted and automated driving systems, which can locate the exact shape of each lane in a traffic scene. Compared with straight lanes, the detection of curved lanes (i.e. "bends") is more critical for further downstream trajectory planning tasks, so that the vehicle can maintain the correct positioning with the road lane when turning in complex road scenes.

[0051] The first determination device 210 determines the curvature and curvature change associated with the curve based on the signal received from the sensor. In one embodiment, the first determination device 210 is configured to: receive signals related to the left and right lane lines of the curve from a video camera sensor with a preprocessing function; and determine the curvature (curvature) and curvature change (curvature change) of the lane centerline based on the signals related to the left and right lane lines. The video camera sensor is, for example, a multi-function camera MPC3, which is installed above the rearview mirror of the vehicle and can clearly monitor the road conditions ahead. In particular, MPC3 combines a multi-path recognition algorithm and artificial intelligence for target recognition, making the results of the perception of the surrounding environment more accurate and reliable, thereby improving road traffic safety.

[0052] For a general curve, each point can be approximated as a small arc. After fixing a point, the reciprocal of the radius of the osculating arc at that point is defined as the curvature of the curve at that point. Therefore, the larger the radius of the osculating arc, the smaller the curvature of the curve, and the closer it is to a straight line. So, the larger the radius of curvature, the smaller the curvature, and vice versa. For a curve, the curvature and / or the change in curvature can be used to determine whether the curve belongs to an "extreme situation" (the vehicle may have a slip angle in the current curve).

[0053] The second determining device 220 is configured to determine a compensation factor according to the curvature and the vehicle speed when the curvature and / or the curvature change is greater than a preset threshold value, and the compensation factor is used to compensate for the influence of the slip angle on the predicted lateral distance. When the curvature and / or the curvature change related to the curve is greater than the preset threshold value (that is, the vehicle orientation and the vehicle movement direction may be inconsistent in the current curve, that is, there is a "slip angle"), the second determining device 220 determines the compensation factor according to the curvature and the vehicle speed, thereby compensating for the influence of the slip angle on the predicted lateral distance. In other words, the compensation factor Factor is a function of the curvature and the vehicle speed. In one embodiment, the compensation factor is obtained from a two-dimensional lookup table based on the curvature and the vehicle speed. The two-dimensional lookup table can be, for example, as shown in the following table.

[0054]

[0055] In one embodiment, the two-dimensional lookup table may be calibrated in advance by using a test vehicle equipped with GPS to measure the lateral distance in a test field.

[0056] In one embodiment, although Figure 2Not shown in the figure, the above-mentioned lateral control device 2000 also includes: a switching device, used to enable the two-dimensional lookup table when the curvature and / or the curvature change is greater than a preset threshold, so that the second determination device 220 can obtain the compensation factor from the two-dimensional lookup table based on the curvature and the vehicle speed, and the compensation factor is adjustable.

[0057] In one embodiment, the control device 230 includes: a calculation unit for calculating the predicted lateral distance DLC of the vehicle to the left / right lane line or the planned driving trajectory based on the compensation factor; and a lateral control unit for performing lateral control based on the predicted lateral distance DLC.

[0058] In one embodiment, the calculation unit determines the predicted lateral distance DLC according to the following formula:

[0059]

[0060] Among them, c0 is a constant, which represents the lateral offset when the predicted longitudinal distance x=0; c1 represents the offset related to the heading angle θ of the vehicle, which is equal to tan(θ); factor is the compensation factor; c2 represents the curvature; and c3 represents the curvature change.

[0061] In one embodiment, the lateral control device 2000 can be integrated into the vehicle motion controller VMC. As the coordinator of the entire chassis system, the VMC not only undertakes the interaction with the ADAS, but also establishes the connection between the various actuators of the chassis, so that the subsystems can interact with each other.

[0062] In one or more embodiments, a vehicle motion controller VMC is integrated in the vehicle, and the vehicle motion controller VMC combines sensor signals (such as lane line information) provided by various sensors (such as a multi-function camera MPC) to perform trajectory planning and control of the vehicle.

[0063] In summary, the lateral control scheme of the embodiment of the present application considers the influence of the slip angle on the predicted lateral distance by determining a (slip angle related) compensation factor according to the curvature and vehicle speed when the curvature and / or curvature change related to the curve is greater than a preset threshold value (i.e., indicating that the vehicle may have a "slip angle" in the current curve); and finally controls the vehicle laterally based on the compensation factor. The above-mentioned lateral control scheme can advantageously compensate for the inaccurate part of the predicted lateral distance caused by the possible misalignment between the vehicle orientation and the vehicle movement direction, especially for "sharp bend" road scenes. In one embodiment, a switch device is added to enable or disable the two-dimensional lookup table to select whether to use slip angle compensation.

[0064] The above examples mainly illustrate the lateral control scheme of the vehicle of the embodiment of the present application. Although only some of the embodiments of the present application are described, it should be understood by those skilled in the art that the present application can be implemented in many other forms without departing from its subject matter and scope. Therefore, the examples and embodiments shown are regarded as illustrative rather than restrictive, and the present application may cover various modifications and substitutions without departing from the spirit and scope of the present application as defined in the claims.

Claims

1. A lateral control method for a vehicle, characterized in that: The method comprises: determining curvature and curvature changes associated with a curve based on signals received from the sensor; When the curvature and / or the curvature change is greater than a preset threshold, determining a compensation factor according to the curvature and the vehicle speed, the compensation factor being used to compensate for the influence of the slip angle on the predicted lateral distance; and The vehicle is laterally controlled based on the compensation factor.

2. The method of claim 1, wherein: The compensation factor is obtained from a two-dimensional lookup table based on the curvature and the vehicle speed.

3. The method of claim 1, wherein: Performing lateral control of the vehicle based on the compensation factor includes: Calculating a predicted lateral distance DLC from the vehicle to a left / right lane line or a planned driving trajectory based on the compensation factor; and Lateral control is performed based on the predicted lateral distance DLC.

4. The method of claim 3, wherein: The predicted lateral distance DLC is determined according to the following formula: Among them, c0 is a constant, which represents the lateral offset when the predicted longitudinal distance x=0; c1 represents the offset related to the heading angle θ of the vehicle, which is equal to tan(θ); factor is the compensation factor; c2 represents the curvature; and c3 represents the curvature change.

5. A lateral control device for a vehicle, characterized in that: The device comprises: a first determining device for determining a curvature and a curvature change associated with a curve based on a signal received from a sensor; a second determining device, for determining a compensation factor according to the curvature and the vehicle speed when the curvature and / or the curvature change is greater than a preset threshold, the compensation factor being used to compensate for the influence of the slip angle on the predicted lateral distance; and A control device is used to laterally control the vehicle based on the compensation factor.

6. The device as claimed in claim 5, further comprising: A switch device is used to enable a two-dimensional lookup table when the curvature and / or the curvature change is greater than a preset threshold, so that the second determination device can obtain the compensation factor from the two-dimensional lookup table based on the curvature and the vehicle speed, and the compensation factor is adjustable.

7. The device of claim 5, wherein: The control device comprises: a calculation unit, configured to calculate a predicted lateral distance DLC from the vehicle to a left / right lane line or a planned driving trajectory based on the compensation factor; and The lateral control unit is used to perform lateral control based on the predicted lateral distance DLC (predict).

8. The device of claim 7, wherein: The calculation unit determines the predicted lateral distance DLC according to the following formula: Among them, c0 is a constant, which represents the lateral offset when the predicted longitudinal distance x=0; c1 represents the offset related to the heading angle θ of the vehicle, which is equal to tan(θ); factor is the compensation factor; c2 represents the curvature; and c3 represents the curvature change.

9. A computer-readable storage medium, characterized in that: The medium includes instructions that, when executed, perform the method of any one of claims 1 to 4.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

11. A vehicle motion controller VMC, characterized in that: The vehicle motion controller VMC comprises a lateral control device as claimed in any one of claims 5 to 8.

12. A vehicle, characterized in that: The vehicle comprises: Sensors; and The vehicle motion controller VMC according to claim 11 is configured to receive sensor signals from the sensors so as to perform trajectory planning and control on the vehicle.

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