Lateral control method and apparatus for vehicle

Abstract

The invention relates to a transverse control method of a vehicle. The method comprises the steps that the transverse gradient of a road surface is received; determining a front wheel steering angle of the vehicle based on the transverse slope of the road surface; and transverse control is conducted on the vehicle through the front wheel steering angle. The application also relates to a lateral control device of a vehicle, a computer storage medium, a computer program product and an advanced driving assistance system (ADAS).

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 storage medium, a computer program product, and an advanced driver assistance system (ADAS). Background Art

[0002] The technologies implemented by autonomous driving control mainly include longitudinal control and lateral control technology of the vehicle. Lateral control refers to control perpendicular to the direction of movement, that is, steering control. For example, lateral control is to achieve path tracking of the autonomous driving car by adjusting the steering wheel angle.

[0003] There are many lateral control algorithms for autonomous vehicles, the most common of which are linear quadratic regulator (LQR), model predictive controller (MPC), PID, etc. In the above algorithms, in order to reduce the steady-state error, in addition to the feedback controller, a feedforward controller is often introduced.

[0004] In actual road design, such as turns and ramps on highways, the road surface is often not horizontal. Generally, the outside is higher and the inside is lower, so that the horizontal component of the road surface's support force on the vehicle provides a part of the centripetal force. However, existing lateral controllers mainly use a linear two-degree-of-freedom vehicle model and do not take the "lateral slope of the road" into consideration, resulting in low accuracy of the final angle control (such as the front wheel steering angle of the vehicle). Summary of the invention

[0005] According to one aspect of the present application, a method for lateral control of a vehicle is provided, the method comprising: receiving a lateral slope of a road surface; determining a front wheel steering angle of the vehicle based on the lateral slope of the road surface; and performing lateral control of the vehicle using the front wheel steering angle.

[0006] As a supplement or alternative to the above solution, in the above method, the lateral slope of the road surface is obtained from a gyroscope or a high-precision map.

[0007] As a supplement or alternative to the above-mentioned scheme, in the above-mentioned method, determining the front wheel steering angle of the vehicle based on the lateral slope of the road surface includes: determining the feedforward value δ of the front wheel steering angle according to the lateral slope θ of the road surface, the curvature radius ρ of the path planned by the feedforward controller, and the vehicle speed u, so as to provide it to the feedforward controller.

[0008] As a supplement or replacement for the above solution, in the above method, the feedforward value δ of the front wheel steering angle is determined according to the following formula: Where K is the stability factor, L is the wheelbase between the front and rear axles, ρ is the radius of curvature of the path planned by the feedforward controller, u is the vehicle speed, and θ is the lateral slope of the road surface.

[0009] According to another aspect of the present application, a lateral control device for a vehicle is provided, the device comprising: a receiving device for receiving a lateral slope of a road surface; a calculating device for determining a front wheel steering angle of the vehicle based on the lateral slope of the road surface; and a control device for using the front wheel steering angle to perform lateral control of the vehicle.

[0010] As a supplement or alternative to the above solution, in the above device, the receiving device is configured to receive the lateral slope of the road surface from a gyroscope or a high-precision map.

[0011] As a supplement or alternative to the above scheme, in the above-mentioned device, the control device includes a feedforward controller, and the calculation device is configured to calculate the feedforward value δ of the front wheel steering angle based on the lateral slope θ of the road surface, the curvature radius ρ of the path planned by the feedforward controller and the vehicle speed u, so as to provide it to the feedforward controller.

[0012] As a supplement or replacement for the above solution, in the above device, the feedforward value δ of the front wheel steering angle is calculated according to the following formula: Where K is the stability factor, L is the wheelbase between the front and rear axles, ρ is the radius of curvature of the path planned by the feedforward controller, u is the vehicle speed, and θ is the lateral slope of the road surface.

[0013] According to another aspect of the present application, a computer storage medium is provided, wherein the medium includes instructions, and the instructions execute the above method when executed.

[0014] 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 as described above is implemented.

[0015] According to yet another aspect of the present application, an advanced driving assistance system (ADAS) is provided. The advanced driving assistance system (ADAS) includes the device as described above.

[0016] The lateral control scheme of the vehicle of the embodiment of the present application determines the front wheel steering angle of the vehicle based on the received lateral slope of the road surface, thereby performing lateral control. Since the scheme takes into account the influence of the lateral slope of the road surface, the front wheel steering angle finally obtained is more accurate and more conducive to the lateral control of the vehicle. In addition, in one or more embodiments of the present application, by providing the (feedforward value of) the front wheel steering angle to a feedforward controller in the lateral control, the control effect can be improved and oscillation and overshoot can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 A schematic flow chart of a lateral control method for a vehicle according to an embodiment of the present application is shown;

[0019] Figure 2 A schematic structural diagram of a lateral control device for a vehicle according to an embodiment of the present application is shown; and

[0020] Figure 3 The transverse slope of a road surface according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] 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.

[0022] 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 includes:

[0023] In step S110, receiving the transverse slope of the road surface;

[0024] In step S120, a front wheel steering angle of the vehicle is determined based on the transverse slope of the road surface; and

[0025] In step S130, the vehicle is laterally controlled using the front wheel steering angle.

[0026] In the context of this application, the lateral control of the vehicle refers to the control perpendicular to the direction of movement of the vehicle, i.e., steering control. In one or more embodiments, the lateral control goal of the vehicle is to control the vehicle to automatically maintain the desired driving route and have good ride comfort and stability under different vehicle speeds, loads, wind resistance, and road conditions.

[0027] In step S110, the transverse slope of the road surface is received. It is understandable that some roads (such as the road surface at turns and ramps on highways) are often not horizontal, and are generally higher on the outside and lower on the inside, so there is a transverse slope of the road surface, such as Figure 3 In one or more embodiments, the transverse slope of the road surface may be obtained from a gyroscope or a high-precision map.

[0028] In step S120, the front wheel steering angle of the vehicle is determined based on the transverse slope of the road surface, and in step S130, the front wheel steering angle is used to control the vehicle laterally. In one or more embodiments, the determined front wheel steering angle is used to provide a feedforward value to a feedforward controller for better lateral control.

[0029] In one embodiment, step S120 includes: determining the feedforward value δ of the front wheel steering angle according to the transverse slope θ of the road surface, the radius of curvature ρ of the path planned by the feedforward controller, and the vehicle speed u, so as to provide it to the feedforward controller. In one embodiment, the feedforward value of the front wheel steering angle can be calculated according to the coefficient mapping table obtained from the transverse slope of the road surface and engineering experience to perform angle control. In order to better consider the dynamic characteristics of different vehicles, in other embodiments, the feedforward value δ of the front wheel steering angle can be derived according to a model or formula. For example, the feedforward value δ of the front wheel steering angle can be determined according to the following formula:

[0030]

[0031] Where K is the stability factor, L is the wheelbase between the front and rear axles, ρ is the radius of curvature of the path planned by the feedforward controller, u is the vehicle speed, and θ is the lateral slope of the road surface.

[0032] In the above formula, K is the stability factor, also known as the stability factor, and its unit is s 2 / m 2 , is a parameter that characterizes the steady-state response of the vehicle, where K = 0 indicates that the vehicle is in neutral steering; when K is greater than 0, the vehicle has understeering characteristics and the yaw rate is controllable; and when K is less than 0, the vehicle has oversteering characteristics and the vehicle will become unstable if it exceeds a certain speed. In one or more embodiments, K is determined by the following formula:

[0033]

[0034] Wherein, m represents the mass of the vehicle, l1 and l2 represent the distances from the center of mass to the front axle and the rear axle respectively, and k1 and k2 represent the lateral stiffness of the front and rear axles. L represents the wheelbase between the front and rear axles, which is equal to l1+l2. In one or more embodiments, K is generally a positive value and can be obtained through road tests.

[0035] Next, combine Figure 3 To illustrate the effect of the road's transverse slope on the steady-state motion of the vehicle. Figure 3 As shown, from the front of the vehicle, θ is the road slope angle, the projection of gravity mg (where g is the acceleration of gravity) on the plane parallel to the road surface mgsin(θ) and the lateral forces Fy1 and Fy2 of the front and rear axles jointly provide the centripetal force. At the same time, the resultant moment of the lateral forces of the front and rear axles at the center of mass relative to the normal direction of the road surface is 0, so the following relationship can be obtained:

[0036] Fy1+Fy2+mgsin(θ)=muω (1)

[0037] Fy1l1=Fy2l2 (2)

[0038] In the above equations (1) and (2), Fy1 and Fy2 represent the lateral forces of the front and rear axles, respectively, and the product of the vehicle speed u and the yaw rate ω is equal to the lateral acceleration. In most operating conditions of autonomous vehicles, the lateral acceleration is less than 0.4g, so the lateral force (lateral force) is proportional to the wheel sideslip angle. Combined with the corresponding relationship between the wheel sideslip angle and the steering angle, the following relationship can be obtained:

[0039]

[0040]

[0041] In the above equations (3) and (4), α1 and α2 are the front and rear wheel sideslip angles, β is the center of mass sideslip angle, and δ is the front wheel steering angle.

[0042] Next, by expressing Fy1 and Fy2 in the above relation (2) using the above relation (3) and (4), we can get the expression of β, which is then substituted into the above relation (1). After formula transformation, we can finally get the following relation (5):

[0043]

[0044] And because the relationship between the yaw angular velocity ω and the path curvature ρ is:

[0045]

[0046] Substituting the above equation (6) into equation (5), we finally get:

[0047]

[0048] In the above equation, gsin(θ)uKL is introduced to consider the influence of the road lateral slope on lateral motion control. By considering the influence of the road lateral slope, a more accurate feedforward wheel steering angle can be obtained, so that the lateral control of the vehicle is also more precise.

[0049] 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 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.

[0050] refer to Figure 2 , Figure 2FIG. 2 shows a schematic structural diagram of a vehicle lateral control device 2000 according to an embodiment of the present application. Figure 2 As shown, the device 2000 includes: a receiving device 210, a computing device 220 and a control device 230. The receiving device 210 is used to receive the transverse slope of the road surface; the computing device 220 is used to determine the front wheel steering angle of the vehicle based on the transverse slope of the road surface; and the control device 230 is used to use the front wheel steering angle to perform lateral control on the vehicle.

[0051] In the context of this application, the lateral control of the vehicle refers to the control perpendicular to the direction of movement of the vehicle, i.e., steering control. In one or more embodiments, the lateral control goal of the vehicle is to control the vehicle to automatically maintain the desired driving route and have good ride comfort and stability under different vehicle speeds, loads, wind resistance, and road conditions.

[0052] In one embodiment, the receiving device 210 is configured to receive the transverse slope of the road surface from a gyroscope or a high-precision map. In one or more embodiments, the control device 230 includes a feedforward controller, and the computing device 220 is configured to calculate the feedforward value δ of the front wheel steering angle according to the transverse slope θ of the road surface, the radius of curvature ρ of the path planned by the feedforward controller, and the vehicle speed u, so as to provide it to the feedforward controller. In one embodiment, the computing device 220 can calculate the feedforward value of the front wheel steering angle according to the coefficient mapping table obtained from the transverse slope of the road surface and engineering experience to perform angle control. In order to better consider the dynamic characteristics of different vehicles, in other embodiments, the feedforward value δ of the front wheel steering angle can be derived according to a model or formula. For example, the feedforward value δ of the front wheel steering angle can be determined according to the following formula:

[0053]

[0054] Where K is the stability factor, L is the wheelbase between the front and rear axles, ρ is the radius of curvature of the path planned by the feedforward controller, u is the vehicle speed, and θ is the lateral slope of the road surface.

[0055] In the above formula, K is the stability factor, also known as the stability factor, and its unit is s2 / m 2 , is a parameter that characterizes the steady-state response of the vehicle, where K = 0 indicates that the vehicle is in neutral steering; when K is greater than 0, the vehicle has understeering characteristics and the yaw rate is controllable; and when K is less than 0, the vehicle has oversteering characteristics and the vehicle will become unstable if it exceeds a certain speed. In one or more embodiments, K is determined by the following formula:

[0056]

[0057] Among them, m represents the mass of the vehicle, l1 and l2 represent the distance from the center of mass to the front and rear axles respectively, and k1 and k2 represent the lateral stiffness of the front and rear axles. L is the wheelbase between the front and rear axles, which is equal to l1+l2. K is generally a positive value and can be obtained through road tests.

[0058] In one embodiment, the lateral control device 2000 of the vehicle can be integrated into various advanced driving assistance systems ADAS. In one embodiment, the advanced driving assistance system ADAS can be installed in a vehicle.

[0059] "Advanced driver assistance system", also known as ADAS or advanced driver assistance system. It uses various sensors installed on the car (such as millimeter wave radar, lidar, single / binocular camera and satellite navigation) to sense the surrounding environment at any time during the car's driving, collect data, identify, detect and track static and dynamic objects, and combine navigation map data to perform systematic calculations and analysis, so as to make the driver aware of possible dangers in advance, effectively increasing the comfort and safety of car driving. In one embodiment, in addition to the lane keeping function, the advanced driving assistance system may also include a navigation and real-time traffic system TMC, an electronic police system ISA (Intelligent speed adaptation or intelligent speed advice), a vehicle network (Vehicular communication systems), an adaptive cruise control ACC (Adaptive cruise control), a lane departure warning system LDWS (Lane departure warning system), a collision avoidance or pre-collision system (Collision avoidance system or Precrash system), a night vision system (Night Vision system), an adaptive light control (Adaptive light control), a pedestrian protection system (Pedestrian protection system), an automatic parking system (Automatic parking), traffic sign recognition (Traffic sign recognition), a blind spot detection (Blind spot detection), a driver fatigue detection (Driver drowsiness detection), a downhill control system (Hill descent control) and an electric vehicle warning sounds (Electric vehicle warning sounds) system, etc.

[0060] In summary, the lateral control scheme of the vehicle of the embodiment of the present application determines the front wheel steering angle of the vehicle based on the received lateral slope of the road surface, thereby performing lateral control. Since the scheme takes into account the influence of the lateral slope of the road surface, the front wheel steering angle finally obtained is more accurate and more conducive to the lateral control of the vehicle. In addition, in one or more embodiments of the present application, by providing the (feedforward value of) the front wheel steering angle to the feedforward controller in the lateral control, the control effect can be improved and oscillation and overshoot can be reduced.

[0061] 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: Receiving road surface transverse slope; Determining a front wheel steering angle of the vehicle based on the transverse slope of the road surface; and The vehicle is laterally controlled using the front wheel steering angle.

2. The method of claim 1, wherein: The transverse slope of the road surface is obtained from a gyroscope or a high-precision map.

3. The method of claim 1, wherein: Determining the front wheel steering angle of the vehicle based on the transverse slope of the road surface comprises: The feedforward value δ of the front wheel steering angle is determined according to the lateral slope θ of the road surface, the curvature radius ρ of the path planned by the feedforward controller, and the vehicle speed u, so as to be provided to the feedforward controller.

4. The method of claim 3, wherein: The feedforward value δ of the front wheel steering angle is determined according to the following formula: Where K is the stability factor, L is the wheelbase between the front and rear axles, ρ is the radius of curvature of the path planned by the feedforward controller, u is the vehicle speed, and θ is the lateral slope of the road surface.

5. A lateral control device for a vehicle, characterized in that: The device comprises: A receiving device, used for receiving the transverse slope of the road surface; A computing device for determining a front wheel steering angle of the vehicle based on a transverse slope of the road surface; and A control device is used to use the front wheel steering angle to control the vehicle laterally.

6. The device of claim 5, wherein: The receiving device is configured to receive the lateral slope of the road surface from a gyroscope or a high-precision map.

7. The device of claim 5, wherein: The control device includes a feedforward controller, and the calculation device is configured to calculate the feedforward value δ of the front wheel steering angle based on the lateral slope θ of the road surface, the curvature radius ρ of the path planned by the feedforward controller, and the vehicle speed u, so as to provide it to the feedforward controller.

8. The device of claim 7, wherein: The feedforward value δ of the front wheel steering angle is calculated according to the following formula: Where K is the stability factor, L is the wheelbase between the front and rear axles, ρ is the radius of curvature of the path planned by the feedforward controller, u is the vehicle speed, and θ is the lateral slope of the road surface.

9. A computer 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. An advanced driver assistance system ADAS, characterized in that: The advanced driver assistance system ADAS comprises the apparatus according to any one of claims 5 to 8.

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