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

Abstract

The embodiment of the invention provides a vehicle steering control method, a controller, a vehicle, a medium and a program product, and the method comprises the steps: obtaining a steering wheel rotation angle and a vehicle longitudinal speed of the vehicle when the vehicle is controlled to steer; according to the steering wheel angle and the vehicle longitudinal speed, target steering control parameters are determined, and control is conducted according to the target steering control parameters; actual steering control parameters of the vehicle are obtained; according to the target steering control parameter and the actual steering control parameter, fast terminal sliding mode control is carried out, and yawing moment and a rear wheel steering angle are generated; according to the yawing moment and the steering angle of the rear wheels, the two first wheels are controlled, and the control stability of the vehicle can be improved through the embodiment of the invention.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle driving control, 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 Art

[0002] At present, when a vehicle is turning, it is usually controlled based on empirical rules. Since the dynamic characteristics of the vehicle are not taken into consideration, it is not suitable for extreme working conditions with complex vehicle dynamic characteristics.

[0003] In addition, some car companies use open-loop control when distributed drive vehicles are turning. Since this does not take the vehicle's lateral dynamics into consideration, it is not suitable for working conditions with high lateral dynamics changes.

[0004] In summary, there is an urgent need for a technical solution that can maintain good handling stability under external interference such as road surface changes and side winds. Summary of the Invention

[0005] In view of the above problems, embodiments of the present invention 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 the above problems or at least partially solve the above problems.

[0006] To solve the above problems, an embodiment of the present invention discloses a steering control method for a vehicle, 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. The steering control method includes:

[0007] When controlling the steering of the vehicle, obtaining a steering wheel angle and a longitudinal speed of the vehicle;

[0008] determining a target steering control parameter according to the steering wheel angle and the longitudinal speed of the vehicle and performing control according to the target steering control parameter;

[0009] Obtaining actual steering control parameters of the vehicle;

[0010] 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;

[0011] The two first wheels are controlled according to the yaw moment and the rear wheel steering angle.

[0012] Optionally, determining a target steering control parameter according to the steering wheel angle and the vehicle longitudinal speed includes:

[0013] A target steering control parameter is determined according to the steering wheel angle, the vehicle longitudinal speed and dynamic model data.

[0014] Optionally, the dynamic model data includes: a two-degree-of-freedom dynamic model and / or a steady-state dynamic model.

[0015] Optionally, determining a target steering control parameter according to the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model includes:

[0016] Make sure the target center of mass sideslip angle is zero;

[0017] A target yaw rate is determined according to the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model.

[0018] Optionally, determining the target yaw rate according to the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model includes:

[0019] Performing stability margin processing on the steady-state dynamics model to determine a redundancy model;

[0020] determining a first yaw rate based on the steering wheel angle, the vehicle longitudinal velocity, and the steady-state dynamics model;

[0021] determining a second yaw rate according to the vehicle longitudinal velocity and the redundancy model;

[0022] A target yaw rate is determined based on the first yaw rate and the second yaw rate.

[0023] Optionally, determining a target yaw rate based on the first yaw rate and the second yaw rate includes:

[0024] The smaller one of the first yaw rate and the second yaw rate is determined as the target yaw rate.

[0025] Optionally, 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 includes:

[0026] determining a control deviation according to the target steering control parameter and the actual steering control parameter;

[0027] Fast terminal sliding mode control is performed based on the control deviation to generate a yaw moment and a rear wheel steering angle.

[0028] Optionally, the actual steering control parameter includes a current sideslip angle of the center of mass and a current yaw rate, and determining the control deviation according to the target steering control parameter and the actual steering control parameter includes:

[0029] Determining a center of mass sideslip angle error based on the target center of mass sideslip angle and the current center of mass sideslip angle;

[0030] determining a yaw rate error according to the target yaw rate and the current yaw rate;

[0031] A control deviation is determined by combining the center of mass sideslip angle error and the yaw rate error.

[0032] Optionally, performing fast terminal sliding mode control based on the control deviation to generate a yaw moment and a rear wheel steering angle includes:

[0033] The fast terminal sliding mode control model receives and processes the control deviation, the current center of mass sideslip angle, and the current yaw rate to obtain a yaw moment and a rear wheel steering angle.

[0034] Optionally, the method further includes:

[0035] determining a terminal sliding surface based on the control deviation;

[0036] determining a sliding mode reaching law according to the terminal sliding mode surface;

[0037] Based on the sliding mode reaching law, the fast terminal sliding mode control model is updated.

[0038] Optionally, controlling the two first wheels according to the yaw moment and the rear wheel steering angle includes:

[0039] 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.

[0040] Optionally, the two first wheels include a right rear wheel and a left rear wheel, and distributing the driving torque to the two first wheels according to the yaw moment and the rear wheel steering angle includes:

[0041] determining a right rear wheel driving torque of the right rear wheel according to the yaw moment and the rear wheel steering angle;

[0042] The left rear wheel driving torque of the left rear wheel is determined according to the yaw moment and the rear wheel steering angle, and the right rear wheel driving torque and the left rear wheel driving torque are in opposite directions.

[0043] Optionally, determining the right rear wheel driving torque of the right rear wheel based on the yaw moment and the rear wheel steering angle includes:

[0044] A ratio of the yaw moment and the rear wheel steering angle is calculated to determine a right rear wheel driving torque of the right rear wheel.

[0045] Optionally, determining the left rear wheel driving torque of the left rear wheel based on the yaw moment and the rear wheel steering angle includes:

[0046] A ratio calculation is performed on the negative value of the yaw moment and the rear wheel steering angle to determine the left rear wheel driving torque of the left rear wheel.

[0047] 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, the steps of the vehicle steering control method described above are implemented.

[0048] A vehicle comprises the vehicle controller described above.

[0049] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the vehicle steering control method described above.

[0050] A computer program product comprises a computer program, which implements the steps of the vehicle steering control method described above when executed by a processor.

[0051] The embodiments of the present invention include the following advantages:

[0052] The embodiment of the present invention obtains the steering wheel angle and the longitudinal speed of the vehicle when controlling the steering of the vehicle; determines the target steering control parameter according to the steering wheel angle and the longitudinal speed of the vehicle and performs control according to the target steering control parameter; obtains the actual steering control parameter of the vehicle; performs fast terminal sliding mode control according to the target steering control parameter and the actual steering control parameter to generate the yaw moment and the rear wheel steering angle; controls the two first wheels according to the yaw moment and the rear wheel steering angle; obtains the steering wheel angle and the longitudinal speed of the vehicle as reference information, and determines the yaw moment and the rear wheel steering angle in combination with the actual steering control parameter. With the yaw moment and the rear wheel steering angle as the control targets, closed-loop coordinated control of the yaw moment torque distribution and the rear wheel steering control is achieved through fast terminal sliding mode control. The fast terminal sliding mode control is used to handle the multi-input and multi-output system control, and the anti-interference advantage of the sliding mode control itself is used to improve the robustness to ensure that the ideal control performance is maintained in the case of external interference. It can overcome the disadvantages of open-loop control, model predictive control, fuzzy control and neural network-based control, reduce the vibration phenomenon in the control process, and improve the vehicle's handling stability; it can cope with driving needs under various complex working conditions, thereby ensuring the vehicle's driving posture and improving the vehicle's handling stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a flowchart of a vehicle steering control method embodiment of the present invention;

[0054] Figure 2 is a flowchart of another embodiment of a vehicle steering control method of the present invention;

[0055] Figure 3 It is a schematic diagram of the vehicle architecture;

[0056] Figure 4 It is a schematic diagram of a two-degree-of-freedom dynamic model;

[0057] Figure 5 2 is a schematic diagram of a control architecture of an example of a vehicle steering control method according to the present invention. DETAILED DESCRIPTION

[0058] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] Reference Figure 1, shows a flowchart of the steps of an embodiment of a vehicle steering control method according to the present invention. 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. Each first wheel can be independently steered, i.e., the two first wheels steer independently of each other and do not steer together. Each first wheel has a corresponding drive source, and the corresponding first wheel is driven to rotate by the different drive sources. If the drive source is a motor, each motor drives the corresponding first wheel to rotate.

[0060] The vehicle steering control method may specifically include the following steps:

[0061] Step 101, when controlling the steering of the vehicle, obtaining the steering wheel angle and the longitudinal speed of the vehicle;

[0062] When it is detected that the vehicle has a turning movement, that is, when controlling the steering of the vehicle, the steering wheel angle and the longitudinal speed of the vehicle can be obtained. The steering wheel angle refers to the angle at which the driver adjusts the steering wheel during the driving of the vehicle. The steering wheel angle reflects the driver's intention for the driving direction of the vehicle and the steering state of the vehicle. The steering wheel angle is the deflection angle of the steering wheel relative to the initial position (usually the horizontal position). Clockwise deflection is a positive value, and counterclockwise deflection is a negative value. The longitudinal speed of the vehicle refers to the velocity component of the center of mass of the vehicle in the driving direction, that is, the speed at which the vehicle is moving. This speed reflects the motion state and driving performance of the vehicle. The longitudinal speed of the vehicle is the component of the center of mass velocity along the driving direction (x-axis) of the vehicle.

[0063] Step 102, determining a target steering control parameter according to the steering wheel angle and the vehicle longitudinal speed, and performing control according to the target steering control parameter;

[0064] The target steering control parameter can be determined based on the steering wheel angle and the vehicle's longitudinal velocity. The target steering control parameter represents the desired control state for the vehicle during steering. The vehicle is then controlled based on the target steering control parameter.

[0065] Step 103, obtaining actual steering control parameters of the vehicle;

[0066] The actual steering control parameters of the vehicle can be obtained, and the actual steering control parameters of the vehicle are corresponding real-time steering control parameters when the vehicle is currently turning.

[0067] Step 104: Perform fast terminal sliding mode control based on the target steering control parameter and the actual steering control parameter to generate a yaw moment and a rear wheel steering angle;

[0068] Fast terminal sliding mode control can be performed using the target steering control parameters and actual steering control parameters to determine the yaw moment and rear wheel steering angle required to achieve the target state. The yaw moment is a force that rotates the vehicle about the Z axis, causing the vehicle to rotate horizontally. When the vehicle needs to turn, the driver turns the steering wheel, causing the front wheels to turn. The tires deform due to friction with the ground, generating a slip angle and lateral force. This lateral force exerts a moment on the vehicle's center of mass in the horizontal plane, known as the yaw moment, causing the vehicle to rotate about its center of mass, resulting in yaw motion. The rear wheel steering angle refers to the angle of deflection of the rear wheels relative to the vehicle's longitudinal axis during steering. Fast terminal sliding mode control aims to converge the vehicle's steering state from the actual steering control parameters to the target steering control parameters within a finite time.

[0069] Step 105: Control the two first wheels according to the yaw moment and the rear wheel steering angle.

[0070] The first wheel can be controlled based on the obtained yaw moment and the rear wheel steering angle. The control parameters include but are not limited to steering angle control and torque control.

[0071] The embodiment of the present invention obtains the steering wheel angle and the longitudinal speed of the vehicle when controlling the steering of the vehicle; determines the target steering control parameter according to the steering wheel angle and the longitudinal speed of the vehicle and performs control according to the target steering control parameter; obtains the actual steering control parameter of the vehicle; performs fast terminal sliding mode control according to the target steering control parameter and the actual steering control parameter to generate the yaw moment and the rear wheel steering angle; controls the two first wheels according to the yaw moment and the rear wheel steering angle; obtains the steering wheel angle and the longitudinal speed of the vehicle as reference information, and determines the yaw moment and the rear wheel steering angle in combination with the actual steering control parameter. With the yaw moment and the rear wheel steering angle as the control targets, closed-loop coordinated control of the yaw moment torque distribution and the rear wheel steering control is achieved through fast terminal sliding mode control. The fast terminal sliding mode control is used to handle the multi-input and multi-output system control, and the anti-interference advantage of the sliding mode control itself is used to improve the robustness to ensure that the ideal control performance is maintained in the case of external interference. It can overcome the disadvantages of open-loop control, model predictive control, fuzzy control and neural network-based control, reduce the vibration phenomenon in the control process, and improve the vehicle's handling stability; it can cope with driving needs under various complex working conditions, thereby ensuring the vehicle's driving posture and improving the vehicle's handling stability.

[0072] Reference Figure 2 , shows a flowchart of another embodiment of a vehicle steering control method of the present invention. In order to more clearly illustrate the corresponding symbols of the control parameters in the embodiment of the present invention, the symbols involved and their meanings are explained below. Please refer to the following Table 1:

[0073] symbol meaning <![CDATA[β d Oh, oh d ]]> Target center of mass sideslip angle, target yaw rate β, ω Actual center of mass sideslip angle, actual yaw rate <![CDATA[β e Oh, oh e ]]> Center of mass sideslip angle error, yaw rate error ΔM Yaw moment <![CDATA[δ r ]]> Rear wheel steering angle <![CDATA[δ f ]]> Front wheel steering angle v Vehicle longitudinal speed

[0074] Table 1

[0075] 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. In an example of the present invention, the vehicle is a three-motor distributed drive vehicle with independent rearward steering capability. The architecture of the vehicle can be referred to Figure 3 The vehicle's front axle is equipped with one wheel-drive motor, and the vehicle's rear axle is equipped with two wheel-drive motors, that is, each of the two rear wheels on the rear axle is equipped with a wheel-drive motor. The two rear wheels are referred to as first wheels. The two first wheels include a right rear wheel and a left rear wheel.

[0076] The vehicle steering control method may specifically include the following steps:

[0077] Step 201, when controlling the steering of the vehicle, obtaining the steering wheel angle and the longitudinal speed of the vehicle;

[0078] When the vehicle is turning, the steering wheel angle and longitudinal speed of the vehicle can be detected by sensors on the vehicle.

[0079] Step 202, determining a target steering control parameter based on the steering wheel angle, the vehicle longitudinal speed, and dynamic model data, and performing control based on the target steering control parameter;

[0080] The dynamic model data describing the operating state of the distributed drive vehicle can be determined first. The dynamic model data is the expression corresponding to the dynamic model. The dynamic model is a dynamic model of the vehicle, which is a mathematical expression of the motion law and mechanical characteristics of the vehicle under various working conditions. The dynamic model can be a two-degree-of-freedom model, a seven-degree-of-freedom model, an eleven-degree-of-freedom model, etc. The embodiment of the present invention is not specifically limited, wherein the two-degree-of-freedom model only includes the two degrees of freedom of the vehicle's lateral and yaw. The seven-degree-of-freedom model includes the longitudinal displacement, lateral displacement and yaw angular velocity of the vehicle body, as well as the rotational motion of the four wheels. The eleven-degree-of-freedom model adds the pitch motion of the vehicle body and the influence of the front wheel angle on the basis of the seven-degree-of-freedom model.

[0081] Furthermore, a two-degree-of-freedom dynamics model and / or a steady-state dynamics model. Since the two-degree-of-freedom dynamics model only has two degrees of freedom, namely, lateral and yaw, it can focus on the lateral handling performance and stability of the vehicle. Therefore, the data corresponding to the two-degree-of-freedom dynamics model can be used as the dynamics model data of the distributed drive vehicle. The two-degree-of-freedom dynamics model of the vehicle can refer to Figure 4, which represents the ideal process of vehicle lateral motion, 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 mass sideslip angle and yaw angular velocity are obtained through steady-state assumptions.

[0082] like Figure 4 The two-degree-of-freedom vehicle dynamics model shown assumes a constant longitudinal velocity along the x-axis, considering only the vehicle's in-plane lateral motion along the y-axis and yaw motion around the z-axis. Air resistance, the effects of the suspension, and the steering system are neglected. The vehicle's center of mass is used as the origin of the vehicle coordinate system. All four wheels have identical tires. Based on Newton's second law and torque balance, the two-degree-of-freedom vehicle dynamics equations, which incorporate direct yaw torque control of the distributed drive motor and four-wheel steering control under the small-angle assumption, are derived as follows:

[0083]

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

[0085] The steady-state dynamics model is a dynamics model in which the two-degree-of-freedom dynamics model is in a stable state.

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

[0087] The target steering control parameters may include a target sideslip angle of the center of mass and a target yaw rate.

[0088] The slip angle is the angle between the center of mass velocity and the vehicle's longitudinal axis, while the target slip angle is the desired slip angle when the vehicle turns. The yaw rate refers to the rate at which the vehicle's angle changes per unit time as it rotates about 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 value indicates faster rotation, while a smaller value indicates slower rotation. The target yaw rate is the desired yaw rate when the vehicle turns.

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

[0090] The steering wheel angle, vehicle longitudinal speed and dynamic model data can be combined to determine the sideslip angle and target yaw rate corresponding to the steering wheel angle and vehicle longitudinal speed based on the description of the motion under the working condition in the dynamic model data.

[0091] In an embodiment of the present invention, combining the steering wheel angle, the vehicle longitudinal speed, and the dynamic model data to determine a target center-of-mass sideslip angle and a target yaw rate includes: determining a steady-state dynamic model based on the dynamic model data; and determining, based on the steady-state dynamic model, the target center-of-mass sideslip angle and the target yaw rate in combination with the steering wheel angle and the vehicle longitudinal speed.

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

[0093]

[0094] in, c 11 =0,

[0095] The target center of mass sideslip angle β can be calculated based on the vehicle being in a steady state instantaneously d and target yaw rate ω d The steady-state dynamics model of the dynamics model data can be determined first, where the steady state of the vehicle is the state where only the front wheels of the vehicle are turned and the vehicle is in uniform circular motion. That is, in formula (1) and are all zero. The corresponding steady-state kinetic model is:

[0096]

[0097] Then, based on the steady-state dynamics model, the description of the motion in the steady-state dynamics model is used to determine the sideslip angle and target yaw rate corresponding to the current steering wheel angle and vehicle longitudinal speed.

[0098] In an embodiment of the present invention, determining the target center-of-mass sideslip angle and the target yaw rate based on the steady-state dynamics model in combination with the steering wheel angle and the vehicle longitudinal speed includes: determining the target center-of-mass 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 in combination with the steering wheel angle and the vehicle longitudinal speed.

[0099] Generally speaking, in order to improve the stability of the vehicle, the target center of mass side slip angle is set to 0, that is:

[0100] β d =0 (4)

[0101] The target center of mass sideslip angle can be determined to be zero. Then, based on the steady-state dynamics model, the target yaw rate corresponding to the current steering wheel angle and vehicle longitudinal speed is determined.

[0102] Furthermore, based on the steering mechanism's kinematic conversion relationship, the steering wheel angle can be converted into a front wheel steering angle. The front wheel steering angle refers to the offset angle of the front wheels when they reach their left or right extremes. This front wheel steering angle and the vehicle's longitudinal velocity are substituted into the steady-state dynamics model to determine the target yaw rate corresponding to this front wheel steering angle and vehicle longitudinal velocity.

[0103] In the example of the present invention, by solving equation (3), the steady-state kinetic model can be obtained as follows:

[0104]

[0105] The front wheel steering angle and the vehicle longitudinal velocity can be substituted into formula (5) to obtain a target yaw rate.

[0106] In an embodiment of the present invention, determining the target yaw rate based on the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model includes: performing stability margin processing on the steady-state dynamics model to determine a redundant model; substituting the steering wheel angle and the vehicle longitudinal speed into the steady-state dynamics model to determine a first yaw rate; substituting the front wheel steering angle and the vehicle longitudinal speed into the redundant model to determine a second yaw rate; and determining the target yaw rate based on the first yaw rate and the second yaw rate.

[0107] In addition, the vehicle needs to consider the influence of the road adhesion coefficient μ during driving. Specifically, the vehicle should ensure the lateral acceleration a during driving. y ≤μg, from this we can get:

[0108]

[0109] When the vehicle is in steady state, β is very small, so the last two terms in (6) can be ignored, resulting in:

[0110]

[0111] In actual situations, there are many factors that affect vehicle motion. A certain amount of redundancy can be set, such as 15% redundancy, which means that 15% stability redundancy processing is required. The redundancy model is:

[0112]

[0113] The steering wheel angle and the vehicle's longitudinal velocity can be substituted into the steady-state dynamics model, that is, 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 the vehicle's longitudinal velocity can also be substituted into the redundant model. That is, formula (8) is used to obtain the second yaw rate. The second yaw rate is the yaw rate calculated based on the redundant model. The target yaw rate can be determined based on the first and second yaw rates.

[0114] In an example of the present invention, determining the target yaw rate based on the first yaw rate and the second yaw rate includes determining a smaller one of the first yaw rate and the second yaw rate as the target yaw rate.

[0115] The magnitude of the first yaw rate and the second yaw rate can be determined, and the smaller yaw rate is used as the target yaw rate. When the first yaw rate is greater than the second yaw rate, the second yaw rate is determined to be the target yaw rate; when the second yaw rate is greater than the first yaw rate, the first yaw rate is determined to be the target yaw rate.

[0116] In summary, (4), (5) and (8) can be combined to obtain the target yaw rate and target center of mass sideslip angle.

[0117]

[0118] The front wheel steering angle and the vehicle longitudinal speed can be substituted into formula (9) to calculate the target yaw rate and the target sideslip angle of the center of mass.

[0119] Step 203: Acquire actual steering control parameters of the vehicle.

[0120] The actual steering control parameters of the vehicle can be obtained to determine the current steering state of the vehicle. Specifically, the actual steering control parameters include the current center of mass sideslip angle and the current yaw rate. The current center of mass sideslip angle and the current yaw rate can be obtained from corresponding sensors.

[0121] Step 204 : Perform 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.

[0122] The target sideslip angle and target yaw rate can be used as the control targets of fast terminal sliding mode control to determine the yaw moment and rear wheel steering angle that the vehicle needs to achieve.

[0123] In an embodiment of the present invention, performing fast terminal sliding mode control according to the target steering control parameter and the actual steering control parameter to generate the yaw moment and the rear wheel steering angle includes:

[0124] Sub-step 2041, determining a control deviation according to the target steering control parameter and the actual steering control parameter;

[0125] The difference between the target steering control parameter and the actual steering control parameter can be determined to determine the control deviation.

[0126] In an embodiment of the present invention, the actual steering control parameters include a current center of mass sideslip angle and a current yaw rate, and determining the control deviation based on the target steering control parameters and the actual steering control parameters includes: determining a center of mass sideslip angle error based on the target center of mass sideslip angle and the current center of mass sideslip angle; determining a yaw rate error based on the target yaw rate and the current yaw rate; and determining the control deviation in combination with the center of mass sideslip angle error and the yaw rate error.

[0127] The difference between the target center of mass slip angle and the current center of mass slip angle can be calculated as the center of mass slip angle error. The difference between the target yaw rate and the current yaw rate can be calculated as the yaw rate error. The center of mass slip angle error and the yaw rate error are combined as a whole error and used as the control deviation.

[0128] That is, the control deviation e is based on the target state (β d 、ω d ) and the actual current vehicle state (β, ω) are calculated as follows:

[0129]

[0130] Among them, e1 is the sideslip angle error of the center of mass, and e2 is the yaw rate error.

[0131] Sub-step 2042 , performing fast terminal sliding mode control based on the control deviation to generate a yaw moment and a rear wheel steering angle.

[0132] The control deviation can be used to perform fast terminal sliding mode control to determine the yaw moment and rear wheel steering angle of the control target.

[0133] Specifically, fast terminal sliding mode control can be performed based on the control deviation, the current sideslip angle, and the current yaw rate to determine the desired yaw moment and rear wheel steering angle. Specifically, the fast terminal sliding mode control model receives and processes the control deviation, the current sideslip angle, and the current yaw rate to obtain the yaw moment and rear wheel steering angle.

[0134] Furthermore, the fast terminal sliding mode control model can be updated based on the control deviation to improve the control accuracy.

[0135] In one embodiment of the present invention, a terminal sliding mode surface is determined based on the control deviation; a sliding mode convergence law is determined according to the terminal sliding mode surface; and the fast terminal sliding mode control model is updated based on the sliding mode convergence law.

[0136] First, the terminal sliding surface can be determined based on the control deviation. The terminal sliding surface can be integrated using a fast fractional function. That is:

[0137]

[0138] 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 can obtain:

[0139]

[0140] The corresponding sliding mode convergence law is determined based on the terminal sliding surface. The terminal sliding surface can be converged, and the corresponding sliding mode convergence law is:

[0141]

[0142] Among them, (K f1 , K f2 are all greater than 0) are parameters to be calibrated.

[0143] In order to prove the stability of fast terminal sliding mode control, we can construct the Lyapunov function:

[0144]

[0145] Taking the derivative of (14) and combining it with (13) we can get:

[0146]

[0147] According to Lyapunov stability theory, the fast terminal sliding mode control is stable.

[0148] determining a fast terminal sliding mode controller based on the sliding mode reaching law;

[0149] The obtained sliding mode reaching law is designed as the corresponding fast terminal sliding mode controller, and the corresponding fast terminal sliding mode control formula is obtained.

[0150] Furthermore, the fast terminal sliding mode control formula can be obtained from formulas (2), (12), and (13):

[0151]

[0152] Where ΔM is the yaw moment, δ r is the rear wheel steering angle, c 11 =0, I Z is the moment of inertia of the vehicle around the Z axis, m is the vehicle mass, k2 is the equivalent lateral stiffness of the rear axle, b is the distance from the center of mass to the rear axle, v x is the vehicle longitudinal velocity, a1, a2>0, b1, b2>0, p>q, p, q are positive odd numbers, β is the current center of mass sideslip angle, ω is the current yaw rate, e1 is the center of mass sideslip angle error, e2 is the yaw rate error, δ f is the front wheel steering angle, k1 front axle equivalent cornering stiffness,

[0153] The control deviation, the current sideslip angle of the center of mass, and the current yaw rate can be substituted into the fast terminal sliding mode control formula, that is, into the above formula (16), to calculate the yaw moment and the rear wheel steering angle.

[0154] Step 205: Control the two first wheels according to the yaw moment and the rear wheel steering angle;

[0155] After the yaw moment and the rear wheel steering angle are obtained, the yaw moment and the rear wheel steering angle can be used to coordinately control the two first wheels so that the vehicle reaches a target state and turns.

[0156] Specifically, the controlling of the two first wheels according to the yaw moment and the rear wheel steering angle includes: distributing the driving torque of the two first wheels according to the yaw moment and the rear wheel steering angle, and performing torque control according to the distributed torque; and performing steering angle control of the two first wheels according to the rear wheel steering angle.

[0157] After obtaining the yaw moment and the rear wheel steering angle, the yaw moment and the rear wheel steering angle can be used to perform coordinated control of the rear wheel steering and torque distribution.

[0158] For rear-wheel steering, after obtaining the rear-wheel steering angle, a corresponding control signal is generated based on the rear-wheel steering angle and sent to the corresponding rear-wheel steering actuator. Based on this control signal, the rear-wheel steering actuator controls the deflection angle of the rear wheels relative to the vehicle's longitudinal axis to achieve the desired rear-wheel steering angle. During the rear-wheel steering process, 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 provides feedback 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.

[0159] For torque distribution, the yaw moment and the rear wheel steering angle can be used together to distribute torque to the rear wheels of the distributed drive vehicle, so that the rear wheels receive a certain amount of torque for steering, ensuring handling stability during steering.

[0160] In an embodiment of the present invention, 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, and the directions of the right rear wheel driving torque and the left rear wheel driving torque are opposite.

[0161] The yaw moment and rear wheel steering angle can be combined to calculate the right rear wheel drive torque allocated to the vehicle's right rear wheel. The right rear wheel drive torque is the yaw moment required for the vehicle's right rear wheel to achieve when turning.

[0162] Furthermore, determining the right rear wheel dynamic torque based on the yaw moment and the rear wheel steering angle includes: calculating the ratio of the yaw moment and the rear wheel steering angle to determine the right rear wheel driving torque.

[0163] The right rear wheel dynamic torque allocated to the right rear wheel can be determined based on the rear wheel steering angle. The right rear wheel driving torque is determined by calculating the ratio of the yaw moment to the rear wheel steering angle.

[0164] Specifically, calculating the ratio of the yaw moment and the rear wheel steering angle to determine the right rear wheel driving torque includes: calculating the ratio of the yaw moment and the rear wheel steering angle to determine the right rear wheel driving torque based on a first torque calculation formula; the first torque calculation formula is:

[0165]

[0166] Among them, τ rr is the right rear wheel driving torque, ΔM is the yaw moment, R is the wheel radius, w is half of the wheel spacing, δr is the rear wheel steering angle.

[0167] The yaw moment and the rear wheel steering angle can be substituted into formula (17), and the result obtained is the right rear wheel driving torque.

[0168] The right rear wheel driving torque is used to generate a corresponding control signal, which is sent to the rear wheel steering actuator to control the torque of the right rear wheel of the vehicle to reach the right rear wheel driving torque.

[0169] Accordingly, the yaw moment and rear wheel steering angle can be combined to calculate the left rear wheel drive torque allocated to the vehicle's left rear wheel. The left rear wheel drive torque is the yaw moment required for the right and left wheels of the vehicle to achieve when turning.

[0170] The left rear wheel drive torque is used to generate a corresponding control signal and 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.

[0171] Furthermore, determining the left rear wheel driving torque based on the yaw moment and the rear wheel steering angle includes: calculating the ratio of the yaw moment and the rear wheel steering angle to determine the left rear wheel driving torque.

[0172] The left rear wheel dynamic torque allocated to the left rear wheel can be determined based on the rear wheel steering angle. The left rear wheel driving torque is determined by calculating the ratio of the yaw moment to the rear wheel steering angle.

[0173] Specifically, calculating the ratio of the yaw moment and the rear wheel steering angle to determine the left rear wheel driving torque includes:

[0174] The left rear wheel driving torque is determined by calculating the ratio of the yaw moment and the rear wheel steering angle based on a second torque calculation formula; the second torque calculation formula is:

[0175]

[0176] Among them, τ rl is the left rear wheel driving torque, ΔM is the yaw moment, R is the wheel radius, w is half of the wheel spacing, δ r is the rear wheel steering angle.

[0177] The yaw moment and the rear wheel steering angle can be substituted into formula (18), and the result obtained is the left rear wheel driving torque.

[0178] The left rear wheel drive torque is used to generate a corresponding control signal and sent to the rear wheel steering actuator to control the torque of the left rear wheel of the vehicle to reach the left rear wheel drive torque.

[0179] The embodiments of the present invention utilize fast terminal sliding mode control to coordinate yaw moment distribution and rear-wheel steering control for the rear wheels of a distributed drive vehicle. This approach utilizes fast terminal sliding mode control for multi-input, multi-output (MIMO) system control and leverages the inherent interference rejection of sliding mode control to enhance robustness, ensuring optimal control performance despite external disturbances. This approach overcomes the shortcomings of open-loop control, model predictive control, fuzzy control, and neural network-based control, reduces chattering during the control process, and improves vehicle handling stability. Fast terminal sliding mode control ensures rapid convergence of vehicle states within a finite timeframe, effectively addressing the lack of dynamic feedback inherent in open-loop control. Furthermore, fast terminal sliding mode control has a low computational burden, making it easier to implement in vehicle control systems with high real-time requirements. Furthermore, fast terminal sliding mode control does not require complex models or extensive training data, avoiding the model inaccuracies and data dependence inherent in fuzzy and neural network control, making it more suitable for vehicle control scenarios.

[0180] In order to make the implementation process of the embodiment of the present invention clear to those skilled in the art, reference can be made to Figure 5 , to illustrate with an example:

[0181] S1: Based on the ideal reference model (i.e., the dynamic model), the target center of mass sideslip angle and target yaw rate are calculated according to the steering wheel angle input by the driver and the actual vehicle speed.

[0182] S2: Calculate the center of mass sideslip angle error and yaw rate error.

[0183] S3: Designing a fast terminal sliding mode controller may include S301: Designing a terminal sliding mode surface. S302: Designing a sliding mode reaching law to obtain a fast terminal sliding mode controller. Yaw torque and rear wheel steering angle are obtained based on the fast terminal sliding mode controller.

[0184] S4: Distributed drive torque distribution.

[0185] It should be noted that for the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0186] An embodiment of the present invention also discloses a vehicle controller, comprising 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, the steps of the vehicle steering control method described above are implemented.

[0187] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage. Alternatively, the memory may be at least one storage device located away from the processor.

[0188] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0189] An embodiment of the present invention further discloses a vehicle, comprising the vehicle controller as described above.

[0190] An embodiment of the present invention further discloses a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the vehicle steering control method described above are implemented.

[0191] A computer program product comprises a computer program, which implements the steps of the vehicle steering control method described above when executed by a processor.

[0192] As for the above embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0193] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0194] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, apparatus, or computer program products. Thus, embodiments of the present invention may take the form of a fully hardware embodiment, a fully software embodiment, or an embodiment combining software and hardware. Furthermore, embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0195] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the process in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0196] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0197] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0198] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0199] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device that includes the element.

[0200] The above is a detailed introduction to a vehicle steering control method, a vehicle controller, a vehicle, a computer-readable storage medium and a computer program product provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A vehicle steering control method, characterized in that: 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 comprising: When controlling the steering of the vehicle, obtaining a steering wheel angle and a longitudinal speed of the vehicle; determining a target steering control parameter according to the steering wheel angle and the longitudinal speed of the vehicle and performing control according to the target steering control parameter; Obtaining actual steering control parameters 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; The two first wheels are controlled according to the yaw moment and the rear wheel steering angle.

2. The method according to claim 1, characterized in that The determining of the target steering control parameter according to the steering wheel angle and the longitudinal speed of the vehicle includes: A target steering control parameter is determined according to the steering wheel angle, the vehicle longitudinal speed and dynamic model data.

3. The method according to claim 2, characterized in that 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, characterized in that The determining of the target steering control parameter according to the steering wheel angle, the vehicle longitudinal speed and the steady-state dynamics model includes: Make sure the target center of mass sideslip angle is zero; A target yaw rate is determined according to the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model.

5. The method according to claim 4, characterized in that Determining the target yaw rate according to the steering wheel angle, the vehicle longitudinal speed, and the steady-state dynamics model includes: Performing stability margin processing on the steady-state dynamics model to determine a redundancy model; determining a first yaw rate based on the steering wheel angle, the vehicle longitudinal velocity, and the steady-state dynamics model; determining a second yaw rate according to the vehicle longitudinal velocity and the redundancy model; A target yaw rate is determined based on the first yaw rate and the second yaw rate.

6. The method according to claim 5, characterized in that The determining a target yaw rate based on the first yaw rate and the second yaw rate includes: The smaller one of the first yaw rate and the second yaw rate is determined as the target yaw rate.

7. The method according to claim 3, characterized in that The performing of 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 includes: determining a control deviation according to the target steering control parameter and the actual steering control parameter; Fast terminal sliding mode control is performed based on the control deviation to generate a yaw moment and a rear wheel steering angle.

8. The method according to claim 7, characterized in that The actual steering control parameter includes a current sideslip angle of the center of mass and a current yaw rate, and determining the control deviation according to the target steering control parameter and the actual steering control parameter includes: Determining a center of mass sideslip angle error based on the target center of mass sideslip angle and the current center of mass sideslip angle; determining a yaw rate error according to the target yaw rate and the current yaw rate; A control deviation is determined by combining the center of mass sideslip angle error and the yaw rate error.

9. The method according to claim 8, characterized in that The performing of fast terminal sliding mode control based on the control deviation to generate a yaw moment and a rear wheel steering angle includes: The fast terminal sliding mode control model receives and processes the control deviation, the current center of mass sideslip angle, and the current yaw rate to obtain a yaw moment and a rear wheel steering angle.

10. The method according to claim 9, characterized in that The method further comprises: determining a terminal sliding surface based on the control deviation; determining a sliding mode reaching law according to the terminal sliding mode surface; Based on the sliding mode reaching law, the fast terminal sliding mode control model is updated.

11. The method according to claim 1, wherein The controlling of the two first wheels according to 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, characterized in that The two first wheels include a right rear wheel and a left rear wheel, and the driving torque of the two first wheels is distributed according to the yaw moment and the rear wheel steering angle, including: determining a right rear wheel driving torque of the right rear wheel according to the yaw moment and the rear wheel steering angle; The left rear wheel driving torque of the left rear wheel is determined according to the yaw moment and the rear wheel steering angle, and the right rear wheel driving torque and the left rear wheel driving torque are in opposite directions.

13. The method according to claim 12, characterized in that Determining the right rear wheel driving torque of the right rear wheel based on the yaw moment and the rear wheel steering angle includes: A ratio of the yaw moment and the rear wheel steering angle is calculated to determine a right rear wheel driving torque of the right rear wheel.

14. The method according to claim 12, characterized in that Determining the left rear wheel driving torque of the left rear wheel based on the yaw moment and the rear wheel steering angle includes: A ratio calculation is performed on the negative value of the yaw moment and the rear wheel steering angle to determine the left rear wheel driving torque of the left rear wheel.

15. A vehicle controller, characterized in that: The invention comprises a processor, a memory and a computer program stored in the memory and capable of running on the processor, wherein when the computer program is executed by the processor, the steps of the vehicle steering control method according to any one of claims 1 to 14 are implemented.

16. A vehicle, characterized in that: Comprising a vehicle controller as claimed in claim 15.

17. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the vehicle steering control method according to any one of claims 1 to 14 are implemented.

18. A computer program product, characterized in that The invention comprises a computer program which, when executed by a processor, implements the steps of the vehicle steering control method according to any one of claims 1 to 14.

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