Steering control method and controller for vehicle, vehicle, medium, and program product

Abstract

A steering control method and controller for a vehicle, a vehicle, a medium, and a program product. The steering control method comprises: when controlling steering of a vehicle, acquiring a steering wheel angle of the vehicle and a vehicle longitudinal velocity; determining a target steering control parameter according to the steering wheel angle and the vehicle longitudinal velocity, and performing control according to the target steering control parameter; acquiring an actual steering control parameter of the vehicle; performing fast terminal sliding mode control according to the target steering control parameter and the actual steering control parameter to generate a yaw moment and a rear-wheel steering angle; and controlling two first wheels according to the yaw moment and the rear-wheel steering angle.

Description

Vehicle steering control methods, controllers, vehicles, media, and software products

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510125452.0, filed on January 26, 2025, entitled "Steering Control Method, Controller, Vehicle, Medium and Program Product for Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of vehicle driving control technology, and in particular to a vehicle steering control method, a vehicle controller, a vehicle, a computer-readable storage medium, and a computer program product. Background Technology

[0004] Currently, when a vehicle is turning, it is usually controlled using empirical rules. Since the dynamic characteristics of the vehicle are not taken into account, this method is not suitable for extreme conditions where the dynamic characteristics of the vehicle are more complex.

[0005] In addition, some automakers use open-loop control for distributed drive vehicles when turning. Since the lateral dynamics of the vehicle are not taken into account, it is not suitable for operating conditions with high lateral dynamic changes.

[0006] In conclusion, there is an urgent need for a technical solution that maintains good handling stability under external disturbances such as road surface changes and crosswinds. Summary of the Invention

[0007] In view of the above problems, embodiments of this application are proposed to provide a vehicle steering control method, a vehicle controller, a vehicle, a computer-readable storage medium, and a computer program product that overcome or at least partially solve the above problems.

[0008] To address the aforementioned problems, this application discloses a vehicle steering control method. The vehicle includes two first wheels suitable for independent steering control, with the two first wheels located at the front or rear of the vehicle. The steering control method includes:

[0009] When controlling the vehicle's steering, obtain the vehicle's steering wheel angle and longitudinal speed;

[0010] Determine the target steering control parameters based on the steering wheel angle and vehicle longitudinal speed, and then control the vehicle according to the target steering control parameters.

[0011] Obtain the vehicle's actual steering control parameters;

[0012] Based on the target steering control parameters and the actual steering control parameters, rapid terminal sliding mode control is performed to generate yaw moment and rear wheel steering angle;

[0013] The two first wheels are controlled based on the yaw moment and the rear wheel steering angle.

[0014] In some embodiments of this application, determining the target steering control parameters based on the steering wheel angle and the vehicle's longitudinal speed includes:

[0015] The target steering control parameters are determined based on the steering wheel angle, vehicle longitudinal speed, and dynamic model data.

[0016] In some embodiments of this application, the dynamic model data includes: a two-degree-of-freedom dynamic model and / or a steady-state dynamic model.

[0017] In some embodiments of this application, target steering control parameters are determined based on steering wheel angle, vehicle longitudinal velocity, and steady-state dynamics model, including:

[0018] The target's centroid sideslip angle is set to zero.

[0019] The target yaw rate is determined based on the steering wheel angle, vehicle longitudinal velocity, and steady-state dynamics model.

[0020] In some embodiments of this application, determining the target yaw rate based on the steering wheel angle, vehicle longitudinal velocity, and steady-state dynamics model includes:

[0021] The steady-state dynamics model is subjected to stability margin processing to determine the redundancy model;

[0022] The first yaw rate is determined based on the steering wheel angle, vehicle longitudinal velocity, and steady-state dynamics model.

[0023] The second yaw rate is determined based on the vehicle's longitudinal velocity and redundancy model.

[0024] The target yaw rate is determined based on the first yaw rate and the second yaw rate.

[0025] In some embodiments of this application, determining the target yaw rate based on a first yaw rate and a second yaw rate includes:

[0026] The smaller of the first yaw rate and the second yaw rate is determined as the target yaw rate.

[0027] In some embodiments of this application, rapid terminal sliding mode control is performed based on the target steering control parameters and the actual steering control parameters to generate yaw moment and rear wheel steering angle, including:

[0028] Determine the control deviation based on the target steering control parameters and the actual steering control parameters;

[0029] Rapid terminal sliding mode control is performed based on control deviation to generate yaw moment and rear wheel steering angle.

[0030] In some embodiments of this application, the actual steering control parameters include the current sideslip angle and the current yaw rate. The control deviation is determined based on the target steering control parameters and the actual steering control parameters, including:

[0031] Determine the centroid sideslip angle error based on the target centroid sideslip angle and the current centroid sideslip angle;

[0032] Determine the yaw rate error based on the target yaw rate and the current yaw rate;

[0033] The control deviation is determined by combining the error of the center of gravity sideslip angle and the error of the yaw rate.

[0034] In some embodiments of this application, rapid terminal sliding mode control is performed based on control deviation to generate yaw moment and rear wheel steering angle, including:

[0035] The fast terminal sliding mode control model receives and processes the control deviation, the current center of gravity sideslip angle, and the current yaw rate to obtain the yaw moment and the rear wheel steering angle.

[0036] In some embodiments of this application, the method further includes:

[0037] Determine the terminal sliding surface based on control deviation;

[0038] The sliding mode convergence law is determined based on the terminal sliding surface;

[0039] Based on the sliding mode reaching law, the fast terminal sliding mode control model is updated.

[0040] In some embodiments of this application, the two first wheels are controlled based on the yaw moment and the rear wheel steering angle, including:

[0041] The driving torque of the two first wheels is distributed according to the yaw moment and the rear wheel steering angle, and torque control is performed according to the distributed torque; and the steering angle of the two first wheels is controlled according to the rear wheel steering angle.

[0042] In some embodiments of this application, the two first wheels include a right rear wheel and a left rear wheel. The drive torque of the two first wheels is distributed according to the yaw moment and the rear wheel steering angle, including:

[0043] Determine the right rear wheel drive torque based on the yaw moment and the rear wheel steering angle;

[0044] Based on the yaw moment and the rear wheel steering angle, the left rear wheel drive torque is determined, while the right rear wheel drive torque is in the opposite direction to the left rear wheel drive torque.

[0045] In some embodiments of this application, the right rear wheel drive torque is determined based on the yaw moment and the rear wheel steering angle, including:

[0046] The ratio of yaw moment to rear wheel steering angle is calculated to determine the right rear wheel drive torque.

[0047] In some embodiments of this application, the left rear wheel drive torque is determined based on the yaw moment and the rear wheel steering angle, including:

[0048] The ratio of the negative value of the yaw moment to the rear wheel steering angle is calculated to determine the left rear wheel drive torque.

[0049] A vehicle controller includes a processor, a memory, and a computer program stored in the memory and capable of running on the processor. When the computer program is executed by the processor, it implements the steps of the vehicle steering control method described above.

[0050] A vehicle, including the vehicle controller described above.

[0051] A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the vehicle steering control method described above.

[0052] A computer program product includes a computer program that, when executed by a processor, implements the steps of the vehicle steering control method described above.

[0053] The embodiments of this application have the following advantages:

[0054] This application embodiment obtains the vehicle's steering wheel angle and longitudinal velocity when controlling vehicle steering; determines target steering control parameters based on the steering wheel angle and longitudinal velocity, and performs control based on the target steering control parameters; obtains the vehicle's actual steering control parameters; performs rapid terminal sliding mode control based on the target steering control parameters and actual steering control parameters to generate yaw moment and rear wheel steering angle; controls the two first wheels based on the yaw moment and rear wheel steering angle; and determines the yaw moment and rear wheel steering angle by using the obtained steering wheel angle and longitudinal velocity as reference information and combining them with the actual steering control parameters. Using speed as the control target, closed-loop coordinated control of yaw moment torque distribution and rear wheel steering control is achieved through fast terminal sliding mode control. Fast terminal sliding mode control is used to handle multi-input multi-output system control, leveraging the inherent anti-interference advantages of sliding mode control to enhance robustness and ensure ideal control performance under external disturbances. This overcomes the disadvantages of open-loop control, model predictive control, fuzzy control, and neural network-based control, reducing chattering during control and improving vehicle handling stability. It can meet the driving needs under various complex conditions, thereby ensuring the vehicle's driving posture and improving handling stability. Attached Figure Description

[0055] Figure 1 is a flowchart of the steps of an embodiment of a vehicle steering control method according to this application;

[0056] Figure 2 is a flowchart of another embodiment of the vehicle steering control method of this application;

[0057] Figure 3 is a schematic diagram of the vehicle architecture;

[0058] Figure 4 is a schematic diagram of the two-degree-of-freedom dynamic model;

[0059] Figure 5 is a schematic diagram of the control architecture of an example of a vehicle steering control method according to this application. Detailed Implementation

[0060] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] Referring to Figure 1, a flowchart illustrating an embodiment of a vehicle steering control method according to this application is shown. The vehicle includes two first wheels suitable for independent steering control, located at the front or rear of the vehicle. Each first wheel can be independently steered, meaning the steering of the two first wheels is relatively independent and not a joint steering. Each first wheel has a corresponding drive source, and different drive sources drive the corresponding first wheel to rotate. For example, if the drive source is a motor, each motor drives the corresponding first wheel to rotate.

[0062] The vehicle steering control method may specifically include the following steps:

[0063] Step 101: When controlling the vehicle's steering, obtain the vehicle's steering wheel angle and longitudinal speed;

[0064] When vehicle steering movement is detected, i.e., when controlling the vehicle's steering, the steering wheel angle and vehicle longitudinal velocity can be obtained. The steering wheel angle refers to the angle at which the driver adjusts the steering wheel during vehicle movement. The steering wheel angle reflects the driver's intention regarding the vehicle's direction of travel and the vehicle's steering state. The steering wheel angle is the deflection angle of the steering wheel relative to its initial position (usually horizontal). Clockwise deflection is positive, and counterclockwise deflection is negative. The vehicle longitudinal velocity refers to the velocity component of the vehicle's center of gravity along the direction of travel, i.e., the vehicle's forward speed. This velocity reflects the vehicle's motion state and driving performance. The vehicle longitudinal velocity is the component of the center of gravity's velocity along the vehicle's direction of travel (x-axis).

[0065] Step 102: Determine the target steering control parameters based on the steering wheel angle and vehicle longitudinal speed, and perform control according to the target steering control parameters;

[0066] The target steering control parameters can be determined by processing the steering wheel angle and the vehicle's longitudinal speed. These parameters characterize the desired control state the vehicle needs to achieve during steering. The vehicle is then controlled based on these target steering control parameters.

[0067] Step 103: Obtain the actual steering control parameters of the vehicle;

[0068] It can obtain the vehicle's actual steering control parameters, which are the real-time steering control parameters corresponding to the vehicle's current steering when it is turning.

[0069] Step 104: Based on the target steering control parameters and the actual steering control parameters, perform rapid terminal sliding mode control to generate yaw moment and rear wheel steering angle;

[0070] Rapid terminal sliding mode control can be performed using both target and actual steering control parameters to determine the yaw moment and rear wheel steering angle required to bring the vehicle to the target state. Yaw moment is the torque that causes the vehicle to rotate around the Z-axis, resulting in a tendency for horizontal rotation. When the vehicle needs to turn, the driver turns the steering wheel, causing the front wheels to turn and the tires to deform due to friction with the ground, generating a slip angle and lateral force. This lateral force generates a torque on the vehicle's center of gravity in the horizontal plane, i.e., the yaw moment, causing the vehicle to rotate around its center of gravity, resulting in yaw motion. The rear wheel steering angle refers to the deflection angle of the rear wheels relative to the vehicle's longitudinal axis during steering. Rapid terminal sliding mode control converges the vehicle's steering state from the actual steering control parameters to the target steering control parameters within a finite time.

[0071] Step 105: Control the two first wheels based on the yaw moment and the rear wheel steering angle.

[0072] The first wheel can be controlled based on the obtained yaw moment and rear wheel steering angle. The controlled parameters include, but are not limited to, steering angle control and torque control.

[0073] This application embodiment obtains the vehicle's steering wheel angle and longitudinal velocity when controlling vehicle steering; determines target steering control parameters based on the steering wheel angle and longitudinal velocity, and performs control based on the target steering control parameters; obtains the vehicle's actual steering control parameters; performs rapid terminal sliding mode control based on the target steering control parameters and actual steering control parameters to generate yaw moment and rear wheel steering angle; controls the two first wheels based on the yaw moment and rear wheel steering angle; and determines the yaw moment and rear wheel steering angle by using the obtained steering wheel angle and longitudinal velocity as reference information and combining them with the actual steering control parameters. Using speed as the control target, closed-loop coordinated control of yaw moment torque distribution and rear wheel steering control is achieved through fast terminal sliding mode control. Fast terminal sliding mode control is used to handle multi-input multi-output system control, leveraging the inherent anti-interference advantages of sliding mode control to enhance robustness and ensure ideal control performance under external disturbances. This overcomes the disadvantages of open-loop control, model predictive control, fuzzy control, and neural network-based control, reducing chattering during control and improving vehicle handling stability. It can meet the driving needs under various complex conditions, thereby ensuring the vehicle's driving posture and improving handling stability.

[0074] Referring to Figure 2, a flowchart of another embodiment of the vehicle steering control method of this application is shown. To more clearly explain the symbols corresponding to the control parameters in the embodiments of this application, the symbols involved and their meanings are explained below, as shown in Table 1:

[0075] Table 1

[0076] The vehicle includes two first wheels suitable for independent steering control, located at either the front or rear of the vehicle. In the example of this application, the vehicle is a three-motor distributed drive vehicle with independent rear-turning capability. The vehicle's architecture can be referenced to Figure 3, with one wheel-side drive motor configured on the front axle and two wheel-side drive motors configured on the rear axle; that is, each of the two rear wheels on the rear axle is equipped with one wheel-side drive motor. These two rear wheels are the first wheels. The two first wheels include a right rear wheel and a left rear wheel.

[0077] The vehicle steering control method may specifically include the following steps:

[0078] Step 201: When controlling the vehicle's steering, obtain the vehicle's steering wheel angle and longitudinal speed;

[0079] When a vehicle is turning, sensors on the vehicle can detect the steering wheel angle and the vehicle's longitudinal speed.

[0080] Step 202: Determine the target steering control parameters based on the steering wheel angle, vehicle longitudinal speed, and dynamic model data, and perform control based on the target steering control parameters;

[0081] First, the dynamic model data describing the operating state of the distributed drive vehicle can be determined. The dynamic model data is the expression corresponding to the dynamic model. The dynamic model is a mathematical expression of the vehicle's motion laws and mechanical characteristics under various operating conditions. The dynamic model can be a two-degree-of-freedom model, a seven-degree-of-freedom model, or an eleven-degree-of-freedom model, etc. This application does not impose specific limitations on the embodiments. The two-degree-of-freedom model includes only the vehicle's lateral and yaw degrees of freedom. The seven-degree-of-freedom model includes the vehicle's longitudinal displacement, lateral displacement, and yaw rate, as well as the rotational motion of the four wheels. The eleven-degree-of-freedom model, based on the seven-degree-of-freedom model, adds the effects of the vehicle's pitch motion and the front wheel steering angle.

[0082] Furthermore, the dynamic model data includes a two-degree-of-freedom dynamic model and / or a steady-state dynamic model. Since the two-degree-of-freedom dynamic model only has two degrees of freedom—lateral and yaw—it can focus on the vehicle's lateral handling performance and stability. Therefore, the data corresponding to the two-degree-of-freedom dynamic model can be used as the dynamic model data for distributed drive vehicles. The two-degree-of-freedom dynamic model of the vehicle, as shown in Figure 4, characterizes the ideal process of the vehicle's lateral motion and is often used in vehicle handling stability control as an ideal reference model. Under the conditions of driver steering input and vehicle longitudinal velocity input, the ideal vehicle center-of-gravity sideslip angle and yaw rate are obtained through steady-state assumptions.

[0083] As shown in Figure 4, the two-degree-of-freedom vehicle dynamics model assumes that the longitudinal velocity of the car along the x-axis remains constant, and only considers the lateral motion of the vehicle along the y-axis and the yaw motion around the z-axis in the plane; neglecting the effects of air resistance, suspension, and steering system; taking the vehicle's center of mass as the origin of the vehicle coordinate system; and assuming that all four wheels have identical tires. Based on Newton's second law and torque balance relationships, under the small-angle assumption, the two-degree-of-freedom vehicle dynamics equations considering direct yaw torque control by the distributed drive motor and four-wheel steering control are obtained, as follows:

[0084] Where m is the vehicle mass; k1 and k2 are the equivalent lateral stiffness of the front and rear axles, respectively; a and b are the distances from the center of mass to the front and rear axles, respectively; I Z v is the moment of inertia of the car about the Z-axis; x and v y These represent the vehicle's longitudinal speed and lateral speed, respectively. The meanings of other symbols are shown in Table 1.

[0085] A steady-state dynamic model is a dynamic model of a two-degree-of-freedom dynamic model in a stable state.

[0086] The steering wheel angle and vehicle longitudinal velocity can be substituted into the corresponding dynamic model data to calculate the target steering control parameters. The vehicle's steering is then controlled based on these target steering control parameters.

[0087] The target steering control parameters may include the target centroid sideslip angle and the target yaw rate.

[0088] The sideslip angle is the angle between the direction of the center of gravity velocity and the vehicle's longitudinal axis. The target sideslip angle is the desired sideslip angle to be achieved when the vehicle is turning. Yaw rate refers to the rate at which the vehicle changes angle per unit time when rotating around a vertical axis in a horizontal plane. It describes the vehicle's rotational dynamics around the vertical axis. The magnitude of the yaw rate reflects the speed of the vehicle's rotation; a larger yaw rate indicates a faster rotation, and a smaller yaw rate indicates a slower rotation. The target yaw rate is the desired yaw rate to be achieved when the vehicle is turning.

[0089] The acquired vehicle state information can be combined with dynamic model data, and the target centroid sideslip angle and target yaw rate can be determined based on the description of motion under the corresponding working conditions in the dynamic model data.

[0090] The steering wheel angle, vehicle longitudinal velocity, and dynamic model data can be combined. Based on the description of motion under the working condition in the dynamic model data, the corresponding center of gravity sideslip angle and target yaw rate can be determined at the steering wheel angle and vehicle longitudinal velocity.

[0091] In embodiments of this application, the target center of gravity sideslip angle and target yaw rate are determined by combining steering wheel angle, vehicle longitudinal speed and dynamic model data, including: determining a steady-state dynamic model based on dynamic model data; and determining the target center of gravity sideslip angle and target yaw rate based on the steady-state dynamic model and combining steering wheel angle and vehicle longitudinal speed.

[0092] because, Therefore Substituting it into (1) and rearranging, we get:

[0093] in,

[0094] c 11 =0,

[0095] The target centroid sideslip angle β can be calculated based on the vehicle being in a steady state instantaneously. d and the target yaw rate ω d First, we can determine the steady-state dynamic model of the dynamic model data under steady-state conditions. The steady-state of the vehicle refers to the state where only the front wheels are turning, and the vehicle is moving in uniform circular motion. That is, in formula (1)... and All are zero. The corresponding steady-state dynamic model is:

[0096] Then, based on the steady-state dynamics model, the description of motion in the steady-state dynamics model is used to determine the center of gravity sideslip angle and target yaw rate corresponding to the current steering wheel angle and vehicle longitudinal speed.

[0097] In the embodiments of this application, the target centroid sideslip angle and target yaw rate are determined based on a steady-state dynamics model, combined with the steering wheel angle and the vehicle's longitudinal speed, including: determining the target centroid sideslip angle to be zero based on the steady-state dynamics model; and determining the target yaw rate based on the steady-state dynamics model, combined with the steering wheel angle and the vehicle's longitudinal speed.

[0098] Generally, to improve vehicle stability, the target center of gravity sideslip angle is set to 0, i.e.: β d =0 (4)

[0099] The target's sideslip angle can be set to zero. Then, based on the steady-state dynamics model, the target yaw rate corresponding to the current steering wheel angle and vehicle longitudinal speed can be determined.

[0100] Furthermore, based on the motion conversion relationship of the steering mechanism, the steering wheel angle can be converted into the front wheel steering angle. The front wheel steering angle refers to the offset angle when the front wheels are turned to their extreme left or right positions. Substituting this front wheel steering angle and the vehicle's longitudinal velocity into the steady-state dynamics model, the target yaw rate corresponding to this front wheel steering angle and vehicle longitudinal velocity can be determined.

[0101] In the example of this application, by solving equation (3), the steady-state dynamic model can be obtained as follows:

[0102] The front wheel steering angle and the vehicle longitudinal speed can be substituted into formula (5) to obtain a target yaw rate.

[0103] In embodiments of this application, determining the target yaw rate based on the steering wheel angle, vehicle longitudinal speed, and steady-state dynamics model includes: performing stabilization margin processing on the steady-state dynamics model to determine a redundancy model; substituting the steering wheel angle and vehicle longitudinal speed into the steady-state dynamics model to determine a first yaw rate; substituting the front wheel steering angle and vehicle longitudinal speed into the redundancy model to determine a second yaw rate; and determining the target yaw rate based on the first yaw rate and the second yaw rate.

[0104] Furthermore, the influence of the road surface adhesion coefficient μ needs to be considered during vehicle operation. Specifically, the lateral acceleration a during vehicle operation should be maintained. y ≤μg, therefore we can conclude:

[0105] When the vehicle is in steady state, β is very small, so the last two terms in equation (6) can be ignored, thus obtaining:

[0106] In reality, many factors affect vehicle movement, so a certain redundancy can be set, such as 15% redundancy. This means that 15% stability redundancy processing is required, and the redundancy model is as follows:

[0107] The steering wheel angle and vehicle longitudinal velocity can be substituted into the steady-state dynamics model, i.e., into formula (5), to obtain the first yaw rate. The first yaw rate is the yaw rate calculated based on the steady-state dynamics model. The steering wheel angle and vehicle longitudinal velocity can also be substituted into the redundancy model, i.e., into formula (8), to obtain the second yaw rate. The second yaw rate is the yaw rate calculated based on the redundancy model. The target yaw rate can be determined based on the first and second yaw rates.

[0108] In the example of this application, determining the target yaw rate based on the first yaw rate and the second yaw rate includes: determining the smaller of the first yaw rate and the second yaw rate as the target yaw rate.

[0109] The magnitudes of the first and second yaw angular velocities can be determined, and the smaller yaw angular velocity is taken as the target yaw angular velocity. When the first yaw angular velocity is greater than the second yaw angular velocity, the second yaw angular velocity is determined as the target yaw angular velocity; when the second yaw angular velocity is greater than the first yaw angular velocity, the first yaw angular velocity is determined as the target yaw angular velocity.

[0110] In summary, combining (4), (5), and (8) yields the following calculation method for the target yaw rate and the target centroid sideslip angle:

[0111] The target yaw rate and the target center of gravity sideslip angle can be calculated by substituting the front wheel steering angle and the vehicle longitudinal speed into formula (9).

[0112] Step 203: Obtain the actual steering control parameters of the vehicle.

[0113] The vehicle's actual steering control parameters can be obtained to determine the vehicle's current steering state. Specifically, the actual steering control parameters include the current sideslip angle and the current yaw rate. These parameters can be obtained from the corresponding sensors.

[0114] Step 204: Based on the target steering control parameters and the actual steering control parameters, perform rapid terminal sliding mode control to generate yaw moment and rear wheel steering angle.

[0115] The target centroid sideslip angle and target yaw rate can be used as control targets for rapid terminal sliding mode control to determine the required yaw moment and rear wheel steering angle of the vehicle.

[0116] In the embodiments of this application, rapid terminal sliding mode control is performed based on the target steering control parameters and the actual steering control parameters to generate yaw moment and rear wheel steering angle, including:

[0117] Sub-step 2041: Determine the control deviation based on the target steering control parameters and the actual steering control parameters;

[0118] It can determine the difference between the target steering control parameters and the actual steering control parameters, and thus determine the control deviation.

[0119] In the embodiments of this application, the actual steering control parameters include the current center of gravity sideslip angle and the current yaw rate. The control deviation is determined based on the target steering control parameters and the actual steering control parameters, including: determining the center of gravity sideslip angle error based on the target center of gravity sideslip angle and the current center of gravity sideslip angle; determining the yaw rate error based on the target yaw rate and the current yaw rate; and determining the control deviation by combining the center of gravity sideslip angle error and the yaw rate error.

[0120] The difference between the target's sideslip angle and the current sideslip angle can be calculated as the sideslip angle error. The difference between the target's yaw rate and the current yaw rate can be calculated as the yaw rate error. The sideslip angle error and the yaw rate error are considered as a whole error and used as the control deviation.

[0121] That is, the control deviation e is based on the target state (β) d ω d The values ​​are calculated from the actual current vehicle state (β, ω), and the calculation method is as follows:

[0122] Where e1 is the centroid sideslip angle error and e2 is the yaw rate error.

[0123] Sub-step 2042: Perform rapid terminal sliding mode control based on control deviation to generate yaw moment and rear wheel steering angle.

[0124] Rapid terminal sliding mode control can be performed by controlling the deviation to determine the yaw moment and rear wheel steering angle of the control target.

[0125] Specifically, rapid terminal sliding mode control can be performed based on control deviation, current center of gravity sideslip angle, and current yaw rate to determine the desired yaw moment and rear wheel steering angle. In other words, the rapid terminal sliding mode control model receives and processes control deviation, current center of gravity sideslip angle, and current yaw rate to obtain the yaw moment and rear wheel steering angle.

[0126] Furthermore, the fast terminal sliding mode control model can be updated based on the control deviation, thereby improving the accuracy of control.

[0127] In some embodiments of this application, the terminal sliding surface is determined based on the control deviation; the sliding mode reaching law is determined based on the terminal sliding surface; and the fast terminal sliding mode control model is updated based on the sliding mode reaching law.

[0128] First, the terminal sliding surface can be determined based on the control deviation. The terminal sliding surface can be integralized using a fast fractional function. That is:

[0129] Where a1, a2, b1, and b2 are all greater than 0, p > q, and both p and q are positive odd numbers. Taking the derivative of (10) with respect to time t, we get:

[0130] Based on the terminal sliding surface, the corresponding sliding mode convergence law is determined. The terminal sliding surface can be converged, and the corresponding sliding mode convergence law is:

[0131] Among them, (K) f1 K f2 (All values ​​greater than 0) are parameters to be calibrated.

[0132] To prove the stability of fast terminal sliding mode control, a Lyapunov function can be constructed:

[0133] Differentiating (14) and combining it with (13), we get:

[0134] According to Lyapunov stability theory, fast terminal sliding mode control is stable.

[0135] Based on the sliding mode reaching law, a fast terminal sliding mode controller is determined;

[0136] The obtained sliding mode approach law is designed as the corresponding fast terminal sliding mode controller, and the corresponding fast terminal sliding mode control formula is obtained.

[0137] Furthermore, from equations (2), (12), and (13), the formula for rapid terminal sliding mode control can be obtained as follows:

[0138] Where ΔM is the yaw moment, δ r For the rear wheel steering angle, c 11 =0, I Z Let be the vehicle's moment of inertia about the Z-axis, m be the vehicle's mass, k2 be the equivalent lateral stiffness of the rear axle, b be the distance from the center of mass to the rear axle, and v be the distance from the center of mass to the rear axle. x For the longitudinal speed of the vehicle, a1, a2 > 0, b1, b2 > 0, p > q, where p and q are positive odd numbers, β is the current sideslip angle, ω is the current yaw rate, e1 is the sideslip angle error, e2 is the yaw rate error, and δ f For the front wheel steering angle, k1 front axle equivalent lateral stiffness

[0139] The control deviation, the current center of gravity sideslip angle and the current yaw rate can be substituted into the fast end sliding mode control formula, that is, substituted into the above formula (16), to calculate the yaw moment and the rear wheel steering angle.

[0140] Step 205: Control the two first wheels based on the yaw moment and the rear wheel steering angle;

[0141] After obtaining the yaw moment and the rear wheel steering angle, the two first wheels can be controlled in a coordinated manner using the yaw moment and the rear wheel steering angle to enable the vehicle to achieve the target state and steer.

[0142] Specifically, the two first wheels are controlled according to the yaw moment and the rear wheel steering angle, including: distributing the driving torque of the two first wheels according to the yaw moment and the rear wheel steering angle, and controlling the torque according to the distributed torque; and controlling the steering angle of the two first wheels according to the rear wheel steering angle.

[0143] After obtaining the yaw moment and rear wheel steering angle, the yaw moment and rear wheel steering angle can be used for coordinated control of rear wheel steering and torque distribution.

[0144] For rear-wheel steering, after obtaining the rear-wheel steering angle, a corresponding control signal can be generated and sent to the corresponding rear-wheel steering actuator. The rear-wheel steering actuator then uses this control signal to control the deflection angle of the rear wheels relative to the vehicle's longitudinal axis to achieve the desired rear-wheel steering angle. During rear-wheel steering, sensors monitor the actual steering angle and steering speed of the rear wheels in real time. The controller compares the actual steering angle with the desired rear-wheel steering angle and makes adjustments based on the difference. By continuously adjusting the output of the rear-wheel steering actuator, the actual steering angle of the rear wheels is kept consistent with the desired rear-wheel steering angle.

[0145] For torque distribution, yaw moment and rear wheel steering angle can be used together to distribute torque to the rear wheels of a distributed drive vehicle, so that the rear wheels receive a certain amount of torque for steering, ensuring handling stability during steering.

[0146] In the embodiments of this application, the driving torque of the two first wheels is distributed according to the yaw moment and the rear wheel steering angle, including: determining the right rear wheel driving torque of the right rear wheel according to the yaw moment and the rear wheel steering angle; determining the left rear wheel driving torque of the left rear wheel according to the yaw moment and the rear wheel steering angle, wherein the driving torque of the right rear wheel and the driving torque of the left rear wheel are in opposite directions.

[0147] The yaw moment and rear wheel steering angle can be combined for calculation to determine the right rear wheel drive torque allocated to the right rear wheel of the vehicle. The right rear wheel drive torque is the yaw moment required for the right rear wheel of the vehicle to steer.

[0148] Furthermore, based on the yaw moment and the rear wheel steering angle, the driving torque of the right rear wheel is determined, including: calculating the ratio of the yaw moment and the rear wheel steering angle to determine the driving torque of the right rear wheel.

[0149] The dynamic torque allocated to the right rear wheel can be determined based on the rear wheel steering angle. The drive torque of the right rear wheel is determined by calculating the ratio of the yaw moment to the rear wheel steering angle.

[0150] Specifically, the ratio of yaw moment to rear wheel steering angle is calculated to determine the right rear wheel drive torque, including: determining the right rear wheel drive torque based on the ratio of yaw moment to rear wheel steering angle using a first torque calculation formula; the first torque calculation formula is:

[0151] Where, τ rr ΔM is the right rear wheel drive torque, ΔM is the yaw moment, R is the wheel radius, w is half the wheel track, and δ is the yaw moment. r This refers to the rear wheel steering angle.

[0152] The yaw moment and the rear wheel steering angle can be substituted into formula (17) to obtain the right rear wheel drive torque.

[0153] The right rear wheel drive torque is used to generate a corresponding control signal, which is then sent to the rear wheel steering actuator to control the torque of the vehicle's right rear wheel to reach the right rear wheel drive torque.

[0154] Accordingly, the yaw moment and rear wheel steering angle can be combined for calculation to determine the left rear wheel drive torque allocated to the left rear wheel of the vehicle. The left rear wheel drive torque is the yaw moment required for the right and left wheels of the vehicle to achieve when steering.

[0155] The left rear wheel drive torque is used to generate a corresponding control signal, which is then sent to the rear wheel steering actuator to control the torque of the left rear wheel of the distributed drive vehicle to reach the left rear wheel drive torque.

[0156] Furthermore, based on the yaw moment and the rear wheel steering angle, the left rear wheel drive torque is determined, including: calculating the ratio of the yaw moment and the rear wheel steering angle to determine the left rear wheel drive torque.

[0157] The dynamic torque allocated to the left rear wheel can be determined based on the rear wheel steering angle. The drive torque of the left rear wheel is determined by calculating the ratio of the yaw moment to the rear wheel steering angle.

[0158] Specifically, the ratio of yaw moment to rear wheel steering angle is calculated to determine the left rear wheel drive torque, including:

[0159] Based on the second torque calculation formula, the ratio of the yaw moment to the rear wheel steering angle is used to determine the left rear wheel drive torque; the second torque calculation formula is as follows:

[0160] Where, τ rl ΔM is the left rear wheel drive torque, ΔM is the yaw moment, R is the wheel radius, w is half the wheel track, and δ is the yaw moment. r This refers to the rear wheel steering angle.

[0161] The yaw moment and the rear wheel steering angle can be substituted into formula (18) to obtain the left rear wheel drive torque.

[0162] The left rear wheel drive torque is used to generate a corresponding control signal, which is then sent to the rear wheel steering actuator to control the torque of the vehicle's left rear wheel to reach the left rear wheel drive torque.

[0163] This application embodiment utilizes fast terminal sliding mode control (FMSC) to coordinate the distribution of yaw moment and the steering of the rear wheels of a distributed drive vehicle. FMSC is used to handle multi-input multi-output system control, leveraging the inherent anti-interference advantages of sliding mode control to enhance robustness and maintain ideal control performance under external disturbances. This overcomes the disadvantages of open-loop control, model predictive control, fuzzy control, and neural network-based control, reducing chattering during control and improving vehicle handling stability. FMSC ensures rapid convergence of the vehicle state within a finite time, effectively solving the problem of lack of dynamic feedback in open-loop control. Furthermore, FMSC has a lower computational burden, making it easier to implement in vehicle control systems with high real-time requirements. FMSC also avoids the problems of model inaccuracy and strong data dependence found in fuzzy control and neural network control, making it more suitable for vehicle control scenarios.

[0164] To enable those skilled in the art to clearly understand the implementation process of the embodiments of this application, an example can be used for illustration with reference to FIG5:

[0165] S1: Based on the ideal reference model (i.e., the dynamic model), calculate the target center of gravity sideslip angle and the target yaw rate according to the steering wheel angle input by the driver and the actual vehicle speed.

[0166] S2: Calculate the error of the centroid side slip angle and the error of the yaw rate.

[0167] S3: Design a fast end-of-line sliding mode controller, which may include S301: Designing the end-of-line sliding surface. S302: Designing the sliding mode reaching law to obtain the fast end-of-line sliding mode controller. Based on the fast end-of-line sliding mode controller, obtain the yaw moment and the rear wheel steering angle.

[0168] S4: Distributed drive torque distribution.

[0169] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of this application.

[0170] This application also discloses a vehicle controller, including a processor, a memory, and a computer program stored in the memory and capable of running on the processor. When the computer program is executed by the processor, it implements the steps of the vehicle steering control method described above.

[0171] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. In some embodiments, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0172] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0173] This application also discloses a vehicle, including the vehicle controller described above.

[0174] This application also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the vehicle steering control method described above.

[0175] A computer program product includes a computer program that, when executed by a processor, implements the steps of the vehicle steering control method described above.

[0176] The above embodiments are basically similar to the method embodiments, so the description is relatively simple. For relevant details, please refer to the description of the method embodiments.

[0177] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0178] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM (Compact Disc Read-Only Memory), optical storage, etc.) containing computer-usable program code.

[0179] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0180] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0181] These computer program instructions may also be loaded onto a computer or other programmable data processing terminal equipment to cause a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable terminal equipment, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0182] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0183] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes the element.

[0184] The foregoing has provided a detailed description of a vehicle steering control method, a vehicle controller, a vehicle, a computer-readable storage medium, and a computer program product provided by this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A vehicle steering control method, wherein, The vehicle includes two first wheels adapted for independent steering control, the two first wheels being located at the front or rear of the vehicle, and the steering control method includes: When controlling the vehicle's steering, the vehicle's steering wheel angle and longitudinal speed are acquired; Based on the steering wheel angle and the vehicle longitudinal speed, the target steering control parameters are determined, and control is performed based on the target steering control parameters; Obtain the actual steering control parameters of the vehicle; Based on the target steering control parameters and the actual steering control parameters, rapid terminal sliding mode control is performed to generate yaw moment and rear wheel steering angle; The two first wheels are controlled based on the yaw moment and the rear wheel steering angle.

2. The method according to claim 1, wherein, Determining the target steering control parameters based on the steering wheel angle and the vehicle's longitudinal speed includes: The target steering control parameters are determined based on the steering wheel angle, the vehicle's longitudinal speed, and the dynamic model data.

3. The method according to claim 2, wherein, The dynamic model data includes: a two-degree-of-freedom dynamic model and / or a steady-state dynamic model.

4. The method according to claim 2, wherein, The step of determining the target steering control parameters based on the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model includes: The target's centroid sideslip angle is set to zero. The target yaw rate is determined based on the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model.

5. The method according to claim 4, wherein, The step of determining the target yaw rate based on the steering wheel angle, the vehicle longitudinal velocity, and the steady-state dynamics model includes: The steady-state dynamic model is subjected to stability margin processing to determine the redundancy model; The first yaw rate is determined based on the steering wheel angle, the vehicle longitudinal velocity, and the steady-state dynamics model. The second yaw rate is determined based on the vehicle's longitudinal velocity and the redundancy model. The target yaw rate is determined based on the first yaw rate and the second yaw rate.

6. The method according to claim 5, wherein, Determining the target yaw rate based on the first yaw rate and the second yaw rate includes: The smaller of the first yaw rate and the second yaw rate is determined as the target yaw rate.

7. The method according to claim 3, wherein, The step of performing rapid end-of-line sliding mode control based on the target steering control parameters and the actual steering control parameters to generate yaw moment and rear wheel steering angle includes: The control deviation is determined based on the target steering control parameters and the actual steering control parameters; Based on the control deviation, rapid terminal sliding mode control is performed to generate yaw moment and rear wheel steering angle.

8. The method according to claim 7, wherein, The actual steering control parameters include the current sideslip angle and the current yaw rate. Determining the control deviation based on the target steering control parameters and the actual steering control parameters includes: Based on the target centroid sideslip angle and the current centroid sideslip angle, determine the centroid sideslip angle error; The yaw rate error is determined based on the target yaw rate and the current yaw rate. The control deviation is determined by combining the centroid side slip angle error and the yaw rate error.

9. The method according to claim 8, wherein, The step of performing rapid terminal sliding mode control based on the control deviation to generate yaw moment and rear wheel steering angle includes: The fast terminal sliding mode control model receives and processes the control deviation, the current centroid sideslip angle, and the current yaw rate to obtain the yaw moment and the rear wheel steering angle.

10. The method according to claim 9, wherein, The method further includes: The terminal sliding surface is determined based on the control deviation; The sliding mode approach law is determined based on the terminal sliding surface; The fast terminal sliding mode control model is updated based on the sliding mode convergence law.

11. The method according to claim 1, wherein, The control of the two first wheels based on the yaw moment and the rear wheel steering angle includes: The driving torque of the two first wheels is distributed according to the yaw moment and the rear wheel steering angle, and torque control is performed according to the distributed torque; and the steering angle of the two first wheels is controlled according to the rear wheel steering angle.

12. The method according to claim 11, wherein, The two first wheels include a right rear wheel and a left rear wheel. The distribution of drive torque between the two first wheels based on the yaw moment and the rear wheel steering angle includes: Based on the yaw moment and the rear wheel steering angle, the right rear wheel drive torque is determined. Based on the yaw moment and the rear wheel steering angle, the left rear wheel drive torque is determined, and the right rear wheel drive torque is in the opposite direction to the left rear wheel drive torque.

13. The method according to claim 12, wherein, Determining the right rear wheel drive torque based on the yaw moment and the rear wheel steering angle includes: The ratio of the yaw moment to the rear wheel steering angle is calculated to determine the right rear wheel drive torque.

14. The method according to claim 12, wherein, The step of determining the left rear wheel drive torque based on the yaw moment and the rear wheel steering angle includes: The ratio of the negative value of the yaw moment to the rear wheel steering angle is calculated to determine the left rear wheel drive torque.

15. A vehicle controller, wherein, It includes a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program, when executed by the processor, implements the steps of the vehicle steering control method as claimed in any one of claims 1 to 14.

16. A vehicle, wherein, Includes the vehicle controller as described in claim 15.

17. A computer-readable storage medium, wherein, A computer program is stored on the computer-readable storage medium, which, when executed by a processor, implements the steps of the vehicle steering control method as described in any one of claims 1 to 14.

18. A computer program product, wherein, It includes a computer program that, when executed by a processor, implements the steps of the vehicle steering control method as described in any one of claims 1 to 14.

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