Transverse control method and system of vehicle, vehicle and equipment
By constructing a system model containing vehicle kinematic model and steering actuator model and solving optimized variables based on the cost function, the output angle delay and steering actuator inertia problems in vehicle lateral control in autonomous driving systems are solved, and higher control accuracy and stability are achieved.
Patent Information
- Application Number
- CN202411677072.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-06-13
AI Technical Summary
The existing autonomous driving system has output angle delay and steering actuator inertia in the vehicle lateral control, resulting in a decrease in control accuracy and stability.
By constructing a system model containing vehicle kinematic model and steering actuator model, and solving optimized variables based on the cost function, the optimal front wheel angle control sequence is obtained, and the steering output delay and actuator model are considered, which improves control accuracy and stability.
It effectively improves the accuracy and stability of vehicle lateral control and controls more in line with the actual vehicle movement state.
Smart Images
Figure CN120135149A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of vehicles, and in particular, to a lateral control method, system, vehicle and device for a vehicle. Background Art
[0002] With the development of science and technology, advanced computer technology, information technology, automatic control technology and artificial intelligence technology have gradually been applied to the field of autonomous driving technology. Vehicle motion control is one of the key technologies of autonomous driving, and at the same time, it is also a basic problem and a necessary condition for researching intelligent vehicles.
[0003] Vehicle motion control is usually based on vehicle dynamics or kinematics models, and feedback control laws are obtained according to different control theories. The Model Predictive Control (MPC) algorithm is often used to design vehicle lateral control. The vehicle is modeled and discretized according to the kinematics model or dynamics model, an optimal control problem is constructed, and a mathematical solver is used to solve it to obtain a high-precision front wheel steering angle.
[0004] The following technical problems exist in the prior art:
[0005] There is a delay in the output steering angle. The delay of general autonomous driving systems is between 20 and 60 ms. Ignoring the output delay for modeling will lead to a decrease in control accuracy and stability.
[0006] The steering actuator has inertia, and the output steering angle needs to pass through a first-order link before acting on the wheels. Directly using the output steering angle for modeling will lead to a decrease in control accuracy and stability. Summary of the Invention
[0007] Based on this, in order to solve the above technical problems, it is necessary to provide a lateral control method, system, vehicle and device for a vehicle, which takes into account the steering output delay and can effectively improve control accuracy and stability, and takes into account the steering actuator model and can control more in line with the actual vehicle motion state.
[0008] In a first aspect, a lateral control method for a vehicle is provided, including:
[0009] Obtain a reference lateral position, a reference heading angle and a reference curvature according to the vehicle position;
[0010] Calculate a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle and the reference curvature;
[0011] Update the issued steering angle sequence according to the steering angle issued in the previous frame of control;
[0012] Construct a system model;
[0013] Solve for optimization variables based on a cost function and the system model;
[0014] According to the solution result, an optimal front wheel steering angle control sequence is obtained, and steering angle control is performed according to the optimal front wheel steering angle control sequence.
[0015] In some examples, the obtaining of the reference lateral position, reference heading angle, and reference curvature according to the vehicle position includes:
[0016] Obtain the vehicle position;
[0017] According to the vehicle position, query the nearest matching point on the planned trajectory to obtain the reference lateral position, reference heading angle, and reference curvature.
[0018] In some examples, the system model includes a vehicle kinematic model and a steering actuator model.
[0019] In some examples, the constructing of the system model includes:
[0020] Construct the vehicle kinematic model and the steering actuator model;
[0021] According to the input delay and the steering actuator model, discretize the vehicle kinematic model to obtain a discrete-time vehicle kinematic model;
[0022] Convert the discrete-time vehicle kinematic model into a delay-free system model.
[0023] In some examples, the solving of the optimization variables based on the cost function and the system model includes:
[0024] Define the cost function;
[0025] According to the cost function and the delay-free system model, solve the optimization variables.
[0026] In some examples, the obtaining of the optimal front wheel steering angle control sequence according to the solution result and the performing of the steering angle control according to the optimal front wheel steering angle control sequence include:
[0027] According to the solution result, obtain the optimal front wheel steering angle control sequence;
[0028] Forward the optimal front wheel steering angle control sequence to the steering actuator to perform steering angle control through the steering actuator.
[0029] In a second aspect, a lateral control system for a vehicle is provided, including:
[0030] An acquisition module, configured to obtain a reference lateral position, a reference heading angle, and a reference curvature according to the vehicle position;
[0031] A calculation module, configured to calculate a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle, and the reference curvature;
[0032] An update module, configured to update the issued steering angle sequence according to the steering angle issued in the previous frame of control;
[0033] A construction module, configured to construct a system model;
[0034] A control module, configured to solve for optimization variables according to a cost function and the system model, and obtain an optimal front-wheel steering angle control sequence according to the solution result, and perform steering angle control according to the optimal front-wheel steering angle control sequence.
[0035] In a third aspect, a vehicle is provided, including: the lateral control system of the vehicle according to the second aspect described above.
[0036] In a fourth aspect, a computer device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the lateral control method of the vehicle in the first aspect and any possible implementation manner of the first aspect are implemented.
[0037] In a fifth aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the steps of the lateral control method of the vehicle in the first aspect and any possible implementation manner of the first aspect are implemented.
[0038] In a sixth aspect, a computer program product is provided, on which a computer program is stored. When the program is executed by a processor, the steps of the lateral control method of the vehicle in the first aspect and any possible implementation manner of the first aspect are implemented.
[0039] By adopting the embodiments of the present application, a reference lateral position, a reference heading angle, and a reference curvature are obtained. According to the reference lateral position, the reference heading angle, and the reference curvature, a lateral position error and a heading angle error are calculated, and the issued steering angle sequence is updated according to the steering angle issued in the previous frame of control, and a system model is constructed, and based on the cost function and the system model, optimization variables are solved. Finally, according to the solution result, an optimal front-wheel steering angle control sequence is obtained, and steering angle control is performed according to the optimal front-wheel steering angle control sequence. Considering the steering output delay, the control accuracy and stability can be effectively improved. Considering the steering actuator model, the control can be more in line with the actual vehicle motion state. Description of the Drawings
[0040] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects, and advantages of the present application will become more apparent:
[0041] Figure 1 It is a flowchart of the lateral control method for a vehicle provided by an embodiment of the present application;
[0042] Figure 2 It is a schematic diagram of the system architecture of the vehicle;
[0043] Figure 3 It is a detailed flowchart of the lateral control method for a vehicle provided by an embodiment of the present application;
[0044] Figure 4 It is a block diagram of the structure of the lateral control system for a vehicle provided by an embodiment of the present application;
[0045] Figure 5 It is a block diagram of the structure of the computer device provided by an embodiment of the present application. Specific embodiments
[0046] The present application will be further described in detail below in conjunction with embodiments and the accompanying drawings. It can be understood that the specific embodiments described herein are only used to explain the related application, rather than limiting the application. Additionally, it should be noted that for ease of description, only parts related to the application are shown in the drawings.
[0047] It should be noted that, without conflict, the embodiments and the features of the embodiments in the present application can be combined with each other. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.
[0048] The lateral control method, system, device, and medium for a vehicle according to an embodiment of the present application will be described in detail below with reference to the drawings.
[0049] Figure 1 It is a flowchart of the lateral control method for a vehicle according to an embodiment of the present application. As Figure 1 shown, the lateral control method for a vehicle according to an embodiment of the present application includes the following steps:
[0050] S101: Obtain a reference lateral position, a reference heading angle, and a reference curvature according to the vehicle position.
[0051] In an embodiment of the present application, obtaining a reference lateral position, a reference heading angle, and a reference curvature according to the vehicle position includes: obtaining the vehicle position; querying the nearest matching point on the planned trajectory according to the vehicle position to obtain the reference lateral position, the reference heading angle, and the reference curvature.
[0052] S102: Calculate a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle, and the reference curvature.
[0053] S103: Update the sequence of steering angles issued according to the steering angle issued in the previous frame of control.
[0054] S104: Build a system model.
[0055] In one embodiment of the present application, the system model includes a vehicle kinematic model and a steering actuator model.
[0056] Further, the building of the system model includes: building the vehicle kinematic model and the steering actuator model; discretizing the vehicle kinematic model according to the input delay and the steering actuator model to obtain a discrete-time vehicle kinematic model; and converting the discrete-time vehicle kinematic model into a delay-free system model.
[0057] S105: Solve for the optimization variables based on the cost function and the system model.
[0058] In one embodiment of the present application, solving for the optimization variables based on the cost function and the system model includes: defining a cost function; and solving for the optimization variables according to the cost function and the delay-free system model.
[0059] S106: Obtain an optimal front-wheel steering angle control sequence according to the solution result, and perform steering angle control according to the optimal front-wheel steering angle control sequence.
[0060] In one embodiment of the present application, obtaining an optimal front-wheel steering angle control sequence according to the solution result and performing steering angle control according to the optimal front-wheel steering angle control sequence includes: obtaining an optimal front-wheel steering angle control sequence according to the solution result; and forwarding the optimal front-wheel steering angle control sequence to a steering actuator to perform steering angle control through the steering actuator.
[0061] In a specific application, as Figure 2 shown, the inputs of the control mainly come from three modules, namely planning, positioning, and chassis. The driving trajectory output by the planning (reference lateral position, reference heading angle, reference curvature). The vehicle state output by the positioning (actual lateral position, actual heading angle, vehicle speed). The actual front-wheel steering angle output by the chassis. The control calculates the lateral error and the heading angle error according to the inputs of the planning, positioning, and chassis, constructs an optimization problem of model predictive control, and solves it to obtain the optimal front-wheel steering angle at the current moment. The control sends the optimal front-wheel steering angle to the CANBUS, and the CANBUS then transfers it to the steering actuator for control.
[0062] As Figure 3 shown, the specific control process is as follows:
[0063] According to the actual vehicle position provided by the positioning, query the nearest matching point on the planned trajectory to obtain the reference lateral position, reference heading angle, and reference curvature.
[0064] Calculate the lateral position error and the heading angle error according to the reference values.
[0065] Update the steering angle sequence according to the steering angle issued in the previous frame control, that is, control the issued steering angle sequence within the output delay time.
[0066] Construct the system model as follows:
[0067] Vehicle kinematic model:
[0068] Assume that the longitudinal speed changes little, decouple the longitudinal and lateral controls, and the kinematic model of the lateral control is as follows:
[0069]
[0070] Where y is the lateral position, θ is the heading angle, v is the speed, L is the wheelbase, and δ is the front wheel steering angle.
[0071] Based on the small angle assumption, it is represented in the state space as follows:
[0072]
[0073] Let the reference lateral position be y ref , and the reference heading angle be θ ref , then the reference model is as follows:
[0074]
[0075] In the above formula, the reference steering angle δ ref cannot be directly obtained. According to the ideal vehicle kinematic model, there is:
[0076] δ ref = κ ref L
[0077] Where κ r e f is the reference curvature.
[0078] Let the lateral error be e y = y - y ref , and the heading angle error be e θ = θ - θ ref , and the error kinematic model of the lateral control can be obtained as follows:
[0079]
[0080] Steering actuator model:
[0081] Use a first-order linear system to approximate the steering actuator model as follows:
[0082]
[0083] Among them, δ r is the actual front wheel steering angle, and τ is the time constant of the steering actuator model.
[0084] Steering actuator model:
[0085] Since there is a certain time delay in transmitting the command of the front wheel steering angle to the steering actuator, usually 20 - 60 ms, or even larger. Commonly used algorithms will ignore this part, resulting in a certain loss of control accuracy and stability.
[0086] Considering the output delay model, as follows:
[0087] δ d (t) = δ(t - τ d )
[0088] Among them, τ d is the delay time, δ d (t) is the front wheel steering angle received by the steering actuator at time t, and δ(t - τ d ) is the front wheel steering angle sent to the steering actuator at time t - τ d .
[0089] Model discretization:
[0090] Considering the input delay and the steering actuator model, the continuous-time vehicle kinematic model becomes:
[0091]
[0092] Let the state quantity be x(t) = [e y (t), e θ (t), δ r (t)] T , and the disturbance quantity be z(t) = κ ref (t), then the model becomes:
[0093]
[0094] Among them,
[0095] For the above model, using the forward difference transformation and discretizing it, we get:
[0096] x(k + 1) = A d x(k) + B d δ(k - N d ) + E d z(k)
[0097] Among them, is the delay step, T is the discrete step (usually taking the algorithm running period, such as 20 ms),
[0098] Thus, a discrete-time vehicle kinematic model is obtained as follows:
[0099]
[0100] To handle the input delay, an augmentation strategy is adopted to convert the above delay system into a delay-free system, and the state variables are extended to:
[0101] x(k) = [e y (k), e θ (k), δ r (k), δ(k - N d ), δ(k - N d + 1), L, δ(k - 1)] T , and the control variable is replaced with δ(k), as follows:
[0102]
[0103] The above model can be expressed by the following equation:
[0104] x(k + 1) = A d x(k) + B d δ(k) + E d z(k)
[0105] where:
[0106]
[0107] Solve the optimization problem as follows:
[0108] After obtaining the system model, it is necessary to define a cost function to solve the optimization variables, as follows:
[0109]
[0110] where J is the cost function, Q f is the weight matrix of the terminal state variables, Q is the weight matrix of the state variables, R is the weight matrix of the control variable, x(k) min and x(k) max are the minimum and maximum values of the state variable x(k) at time k, δ(k) min and δ(k) max are the minimum and maximum values of the control variable δ(k) at time k.
[0111] After constructing the cost function, an optimization problem is constructed according to the solver and solved, and finally the optimal front-wheel steering angle control sequence U opt = [δ opt (0), L, δ opt(N - 1).
[0112] Obtain the optimal front wheel steering angle control sequence U opt = [δ opt (0), L, δ opt (N - 1)]'s first value δ opt (0), and send it to the CANBUS, and the CANBUS then forwards it to the steering actuator for steering angle control.
[0113] According to the lateral control method of the vehicle according to the embodiment of the present application, based on the vehicle position, obtain the reference lateral position, reference heading angle, and reference curvature, calculate the lateral position error and heading angle error according to the reference lateral position, reference heading angle, and reference curvature, update the issued steering angle sequence according to the steering angle issued in the previous frame control, and construct a system model, and based on the cost function and the system model, solve for the optimization variables. Finally, according to the solution result, obtain the optimal front wheel steering angle control sequence, and perform steering angle control according to the optimal front wheel steering angle control sequence. Considering the steering output delay, it can effectively improve the control accuracy and stability. Considering the steering actuator model, it can control more in line with the actual vehicle motion state.
[0114] Figure 4 is the structural block diagram of the lateral control system of the vehicle according to an embodiment of the present application. As Figure 4 shown, the lateral control system of the vehicle according to an embodiment of the present application includes: an acquisition module 410, a calculation module 420, an update module 430, a construction module 440, and a control module 450, where:
[0115] The acquisition module 410 is configured to obtain the reference lateral position, reference heading angle, and reference curvature according to the vehicle position;
[0116] The calculation module 420 is configured to calculate the lateral position error and heading angle error according to the reference lateral position, reference heading angle, and reference curvature;
[0117] The update module 430 is configured to update the issued steering angle sequence according to the steering angle issued in the previous frame control;
[0118] The construction module 440 is configured to construct a system model;
[0119] The control module 450 is configured to solve for the optimization variables according to the cost function and the system model, obtain the optimal front wheel steering angle control sequence according to the solution result, and perform steering angle control according to the optimal front wheel steering angle control sequence.
[0120] The lateral control system of a vehicle according to an embodiment of the present application obtains a reference lateral position, a reference heading angle, and a reference curvature based on the vehicle position, calculates a lateral position error and a heading angle error based on the reference lateral position, the reference heading angle, and the reference curvature, updates the issued steering angle sequence according to the steering angle issued in the previous frame control, constructs a system model, and solves for optimization variables based on a cost function and the system model. Finally, an optimal front-wheel steering angle control sequence is obtained according to the solution result, and steering angle control is performed according to the optimal front-wheel steering angle control sequence. It takes into account the steering output delay and can effectively improve control accuracy and stability. It takes into account the steering actuator model and can control more in line with the actual vehicle motion state.
[0121] For the specific limitations of the lateral control system of the vehicle, reference can be made to the limitations of the vehicle lateral control method described above, which will not be elaborated here. Each module of the above-mentioned vehicle lateral control system can be implemented in whole or in part by software, hardware, and their combination. The above-mentioned each module can be embedded in the processor of the computer device in the form of hardware or independent of it, or stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned each module.
[0122] In one embodiment, a vehicle is provided, including: the lateral control system of the vehicle according to any one of the above embodiments. The vehicle obtains a reference lateral position, a reference heading angle, and a reference curvature based on the vehicle position, calculates a lateral position error and a heading angle error based on the reference lateral position, the reference heading angle, and the reference curvature, updates the issued steering angle sequence according to the steering angle issued in the previous frame control, constructs a system model, and solves for optimization variables based on a cost function and the system model. Finally, an optimal front-wheel steering angle control sequence is obtained according to the solution result, and steering angle control is performed according to the optimal front-wheel steering angle control sequence. It takes into account the steering output delay and can effectively improve control accuracy and stability. It takes into account the steering actuator model and can control more in line with the actual vehicle motion state.
[0123] In addition, the other components and functions of the vehicle according to the embodiments of the present application are known to those of ordinary skill in the art and will not be elaborated here.
[0124] In one embodiment, a computer device is provided. Figure 5 It is the structural block diagram of the computer device provided in the embodiment of the present application. Refer to Figure 5 . The computer device includes a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, it implements the foregoing vehicle lateral control method embodiment. For example, it executes: obtaining a reference lateral position, a reference heading angle, and a reference curvature based on the vehicle position;
[0125] Calculating a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle and the reference curvature;
[0126] Update the issued corner sequence according to the corner issued by the previous frame control;
[0127] Build system models;
[0128] Solving the optimization variables based on the cost function and the system model;
[0129] According to the solution result, an optimal front wheel steering angle control sequence is obtained, and steering angle control is performed according to the optimal front wheel steering angle control sequence.
[0130] The embodiment of the present application further provides a computer-readable storage medium, the computer-readable storage medium stores a computer program, and the processor implements the above-mentioned vehicle lateral control method embodiment when executing the computer program. For example, the following is performed: according to the vehicle position, a reference lateral position, a reference heading angle and a reference curvature are obtained;
[0131] Calculating a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle and the reference curvature;
[0132] Update the issued corner sequence according to the corner issued by the previous frame control;
[0133] Build system models;
[0134] Solving the optimization variables based on the cost function and the system model;
[0135] According to the solution result, an optimal front wheel steering angle control sequence is obtained, and steering angle control is performed according to the optimal front wheel steering angle control sequence.
[0136] The present application embodiment provides a computer program product, which includes instructions. When the instructions are executed, the method described in the embodiment of the present application is executed. For example, it can be executed Figure 1 The various steps of the lateral control method of the vehicle shown, for example, are performed: obtaining a reference lateral position, a reference heading angle, and a reference curvature according to the position of the vehicle;
[0137] Calculating a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle and the reference curvature;
[0138] Update the issued corner sequence according to the corner issued by the previous frame control;
[0139] Build system models;
[0140] Solving the optimization variables based on the cost function and the system model;
[0141] According to the solution result, an optimal front wheel steering angle control sequence is obtained, and steering angle control is performed according to the optimal front wheel steering angle control sequence.
[0142] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.
[0143] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.
[0144] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.
Claims
1. A lateral control method for a vehicle, characterized in that: include: According to the vehicle position, a reference lateral position, a reference heading angle and a reference curvature are obtained; Calculating a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle and the reference curvature; Update the issued corner sequence according to the corner issued by the previous frame control; Build system models; Solving the optimization variables based on the cost function and the system model; According to the solution result, an optimal front wheel steering angle control sequence is obtained, and steering angle control is performed according to the optimal front wheel steering angle control sequence.
2. The lateral control method of a vehicle according to claim 1, characterized in that: The step of obtaining a reference lateral position, a reference heading angle, and a reference curvature according to the vehicle position includes: Get the vehicle position; According to the vehicle position, the nearest matching point on the planned trajectory is queried to obtain the reference lateral position, reference heading angle and reference curvature.
3. The lateral control method of a vehicle according to claim 1, characterized in that: The system model includes a vehicle kinematics model and a steering actuator model.
4. The vehicle lateral control method according to claim 3, characterized in that: The construction of the system model includes: Constructing the vehicle kinematics model and the steering actuator model; Discretizing the vehicle kinematics model according to the input delay and the steering actuator model to obtain a discrete-time vehicle kinematics model; The discrete-time vehicle kinematic model is converted into a delay-free system model.
5. The lateral control method of a vehicle according to claim 4, characterized in that: The solving of optimization variables based on the cost function and the system model includes: Define the cost function; The optimization variables are solved according to the cost function and the delay-free system model.
6. The lateral control method of a vehicle according to claim 1, characterized in that: The method of obtaining an optimal front wheel steering angle control sequence according to the solution result and performing steering angle control according to the optimal front wheel steering angle control sequence comprises: According to the solution results, the optimal front wheel steering angle control sequence is obtained; The optimal front wheel steering angle control sequence is forwarded to the steering actuator so as to perform steering angle control through the steering actuator.
7. A lateral control system for a vehicle, characterized in that: include: An acquisition module, used for obtaining a reference lateral position, a reference heading angle and a reference curvature according to a vehicle position; A calculation module, used for calculating a lateral position error and a heading angle error according to the reference lateral position, the reference heading angle and the reference curvature; An updating module, used for updating a sent corner sequence according to the corner sent by the previous frame; Building blocks, used to construct system models; The control module is used to solve the optimization variables according to the cost function and the system model, obtain the optimal front wheel steering angle control sequence according to the solution result, and perform steering angle control according to the optimal front wheel steering angle control sequence.
8. A vehicle, characterized in that: include: A lateral control system for a vehicle according to claim 7.
9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the lateral control method of the vehicle according to any one of claims 1-6 is implemented.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the lateral control method of the vehicle according to any one of claims 1 to 6 is implemented.