A vehicle drift control method, system, device and medium

Abstract

The application discloses a kind of vehicle drift control method, system, equipment and medium.The method comprises: according to tire force, vehicle state data and balance equation set, the front wheel rotation angle, mass center side slip angle and yaw angular velocity balance point are obtained;Actual mass center side slip angle after the driver based on the front wheel rotation angle balance point operation is obtained;According to actual and balanced mass center side slip angle, gain and yaw angular velocity balance point, target yaw moment is obtained;According to slip rate, target yaw moment, target function is constructed;According to target function and model predictive control algorithm, four-wheel execution torque is obtained.The application solves the problem that stability control cannot meet the demand of drift working condition as the goal of inhibiting sideslip, and realizes steady-state drift control.

Description

Technical Field

[0001] This application relates to the field of vehicle control, specifically to a method, system, device, and medium for controlling vehicle drift. Background Technology

[0002] With the continuous development of vehicle dynamics control technology, four-wheel independent drive vehicles, due to their flexible torque distribution advantages, are gradually becoming an important development direction for high-performance vehicles. Currently, vehicle control systems are widely used to improve vehicle handling stability, while drivers are also placing higher demands on the controllability and driving experience of vehicles under extreme conditions.

[0003] In related technologies, vehicles are typically equipped with electronic stability control systems to monitor the vehicle's driving status. When the system detects a tendency for the vehicle to skid or become unstable, it will actively intervene in power output or apply braking force to restore vehicle stability. Furthermore, some vehicle control strategies tend to have the system completely take over control of the vehicle to achieve a specific driving trajectory.

[0004] However, existing technologies suffer from the technical problem that stability control, which aims to suppress sideslip and restore grip, cannot meet the comprehensive needs of drifting conditions. Traditional stability control logic interrupts the sideslip state required for drifting, while a fully take-over control approach struggles to maintain the driver's sense of participation, making it difficult to achieve sustainable steady-state drift control while ensuring safety. Summary of the Invention

[0005] This application provides a vehicle drift control method, system, device, and medium, which can solve the technical problem that the stability control in the prior art, which aims to suppress sideslip and restore grip, cannot meet the comprehensive needs under drifting conditions.

[0006] In a first aspect, embodiments of this application provide a vehicle drift control method, the vehicle drift control method comprising: Based on the obtained tire force of the target vehicle, the state data of the target vehicle, and the preset state variable balance equation set, the front wheel steering angle balance point, the center of gravity sideslip angle balance point, and the yaw rate balance point of the target vehicle are obtained. Obtain the actual center of gravity sideslip angle after the driver and passengers operate based on the front wheel steering angle balance point; The target yaw torque is obtained based on the actual centroid sideslip angle, the centroid sideslip angle equilibrium point, the preset centroid sideslip angle error feedback gain, the preset yaw rate gain, and the yaw rate equilibrium point. Construct an objective function based on the obtained slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment; Based on the objective function and model predictive control algorithm, the four-wheel execution torque is obtained to achieve vehicle drift control.

[0007] In conjunction with the first aspect, in one implementation, the obtained tire force of the target vehicle includes: Acquire the state data of the target vehicle, which includes the tire resultant force on the X-axis, the tire resultant force on the Y-axis, the vehicle mass, the sideslip angle, the distance between the front axle and the rear axle, the wheel moment of inertia, and the real-time vehicle speed. Based on the obtained distance between the front axle center of gravity and the rear axle center of gravity, the tire slip angle of the front axle and the tire slip angle of the rear axle are obtained. Based on the obtained vehicle weight and vehicle mass, determine the load on each tire; Based on the tire slip angle of the front axle, the tire slip angle of the rear axle, and each tire load, as well as the obtained tire lateral stiffness, preset road adhesion coefficient, and preset Fiala tire model, the tire lateral force is determined. The longitudinal force of the tire is calculated based on the tire lateral force and the pre-set tire mechanics formula; The tire force is obtained by vector synthesis of the tire lateral force and the tire longitudinal force.

[0008] In conjunction with the first aspect, in one implementation, the step of obtaining the front wheel steering angle balance point, center of gravity sideslip angle balance point, and yaw rate balance point of the target vehicle based on the acquired tire forces of the target vehicle, the state data of the target vehicle, and a preset set of state variable balance equations includes: Acquire the state data of the target vehicle, which includes the tire resultant force on the X-axis, the tire resultant force on the Y-axis, the vehicle mass, the sideslip angle, the distance between the front axle and the rear axle, the wheel moment of inertia, and the real-time vehicle speed. The pre-set state variable equilibrium equation set includes the first state variable equilibrium equation set, the second state variable equilibrium equation set, and the third state variable equilibrium equation set; Based on the obtained tire net force on the X-axis, tire net force on the Y-axis, vehicle mass, real-time vehicle speed, center of gravity sideslip angle, and the first state variable balance equation set of the target vehicle, the center of gravity sideslip angle equilibrium point is obtained. Based on the obtained tire net force on the X-axis, tire net force on the Y-axis, vehicle mass, real-time vehicle speed, the center of gravity sideslip angle equilibrium point, and the second state variable equilibrium equation set, the yaw rate equilibrium point is obtained. Based on the obtained tire force, front axle center of mass distance, rear axle center of mass distance, wheel moment of inertia, and the third state variable balance equations of the target vehicle, the front wheel steering angle equilibrium point is obtained.

[0009] In conjunction with the first aspect, in one embodiment, obtaining the actual sideslip angle of the center of gravity after the driver / passenger operates based on the front wheel steering angle balance point includes: A target steering wheel angle is generated based on the front wheel steering angle balance point, so that the driver and passengers can operate the steering wheel based on the target steering wheel angle; Acquire the actual steering wheel angle, real-time vehicle speed, and yaw rate when the driver and passengers are operating the steering wheel; The actual center of gravity sideslip angle is obtained based on the actual steering wheel angle, the real-time vehicle speed, the yaw rate, the acquired vehicle mass, and the vehicle state observer.

[0010] In conjunction with the first aspect, in one embodiment, obtaining the target yaw moment based on the actual sideslip angle, the sideslip angle equilibrium point, a preset sideslip angle error feedback gain, a preset yaw rate gain, and the yaw rate equilibrium point includes: Based on the difference between the actual centroid sideslip angle and the centroid sideslip angle equilibrium point, as well as the obtained preset centroid sideslip angle error feedback gain and the yaw rate equilibrium point, the desired yaw rate is obtained. The target yaw torque is obtained based on the desired yaw rate, the preset yaw rate gain, and the yaw rate equilibrium point.

[0011] In conjunction with the first aspect, in one embodiment, obtaining the target yaw torque based on the desired yaw rate, a preset yaw rate gain, and the yaw rate equilibrium point includes: The desired yaw rate equilibrium point is obtained by the difference between the current yaw rate of the target vehicle and the desired yaw rate, the preset yaw rate gain, and the yaw rate equilibrium point. The target yaw torque is obtained based on the acquired wheel moment of inertia, the desired yaw rate equilibrium point, the preset yaw rate gain, and the difference between the yaw rate and the desired yaw rate.

[0012] In conjunction with the first aspect, in one implementation, constructing the objective function based on the acquired slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment includes: The current slip ratio is obtained by matching the preset two-dimensional lookup table, real-time vehicle speed and actual center of gravity sideslip angle. The wheel speed at the next moment is obtained based on the current wheel speed, the wheel moment of inertia within the preset control cycle, the tire longitudinal force, the tire rolling radius, and the current torque. The slip ratio at the next moment is obtained based on the component of the wheel speed and the vehicle center of gravity speed in the tire plane direction at the next moment. Based on the obtained left wheel track, right wheel track, tire rolling radius, and the difference in driving torque of each wheel, the yaw moment at the next moment is obtained; Based on the difference between the target yaw moment and the yaw moment at the next moment, and the difference between the slip ratio and the slip ratio at the next moment, a tracking term is constructed. The tracking terms are then weighted and combined to obtain the objective function.

[0013] In conjunction with the first aspect, in one implementation, the step of constructing tracking terms based on the difference between the acquired target yaw moment and the yaw moment at the next moment, and the difference between the slip ratio and the slip ratio at the next moment, and then weighting and combining the tracking terms to obtain the objective function, includes: The difference between the target yaw moment and the yaw moment at the next moment is calculated to obtain the yaw moment tracking term; The difference between the obtained slip ratio and the slip ratio at the next moment is calculated to obtain the slip ratio tracking term; The objective function is obtained based on the yaw moment tracking term, the slip ratio tracking term, and the obtained preset weight coefficients.

[0014] In conjunction with the first aspect, in one implementation, obtaining the four-wheel execution torque based on the objective function and the model predictive control algorithm to achieve vehicle drift control includes: Obtain preset four-wheel torque constraint conditions, wherein the four-wheel execution torque is less than or equal to a first preset torque limit value, and the four-wheel execution torque is greater than or equal to a second preset torque limit value; The objective function is solved by rolling optimization based on the model predictive control algorithm and the preset four-wheel torque constraints to obtain the control sequence. The rolling optimization solution process includes calculating the yaw moment corresponding to the torque of the four wheels at the next moment, and minimizing the deviation between the yaw moment at the next moment and the target yaw moment; The first control quantity in the control sequence is decomposed into independent torque commands for the four wheels, thereby obtaining the four-wheel execution torque.

[0015] Secondly, embodiments of this application provide a vehicle drift control system, the system comprising: The equilibrium point calculation module is used to obtain the front wheel steering angle equilibrium point, center of gravity sideslip angle equilibrium point, and yaw rate equilibrium point of the target vehicle based on the obtained tire force of the target vehicle, the state data of the target vehicle, and the preset state variable equilibrium equation set. The steering operation module is used to obtain the actual center of gravity sideslip angle after the driver and passengers operate based on the front wheel steering angle balance point; The torque determination module is used to obtain the target yaw torque based on the actual center of mass sideslip angle, the center of mass sideslip angle equilibrium point, the preset center of mass sideslip angle error feedback gain, the preset yaw rate gain, and the yaw rate equilibrium point. The objective function construction module is used to construct an objective function based on the obtained slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment. The torque distribution module is used to obtain the four-wheel execution torque according to the objective function and the model predictive control algorithm to achieve vehicle drift control.

[0016] Thirdly, embodiments of this application provide a vehicle drift control device, the vehicle drift control device including a processor, a memory, and a vehicle drift control program stored in the memory and executable by the processor, wherein when the vehicle drift control program is executed by the processor, it implements the steps of the vehicle drift control method as described in any one of the above.

[0017] Fourthly, embodiments of this application provide a computer-readable storage medium storing a vehicle drift control program, wherein when the vehicle drift control program is executed by a processor, it implements the steps of the vehicle drift control method as described in any one of the above descriptions.

[0018] The beneficial effects of the technical solutions provided in this application include: By obtaining the tire forces, state data, and preset state variable balance equations of the target vehicle, the front wheel steering angle balance point, center of gravity sideslip angle balance point, and yaw rate balance point of the target vehicle are obtained. The actual center of gravity sideslip angle after the driver and passengers operate based on the front wheel steering angle balance point is then obtained. Based on the actual center of gravity sideslip angle, the center of gravity sideslip angle balance point, the preset center of gravity sideslip angle error feedback gain, the preset yaw rate gain, and the yaw rate balance point, the target yaw moment is obtained. Finally, based on the obtained slip ratio, the slip ratio at the next moment, and the target yaw... The objective function is constructed by the torque and the yaw torque at the next moment. Based on the objective function and the model predictive control algorithm, the torque executed by the four wheels is obtained. This solves the technical problem in related technologies where stability control, which aims to suppress sideslip and restore grip, cannot meet the comprehensive needs under drifting conditions. It achieves the dynamic distribution of torque to the four wheels through model predictive control to maintain steady-state drifting of the vehicle under tire force saturation conditions while retaining the driver's steering participation. This avoids loss of vehicle control and meets the comprehensive needs of controllability, stability and fun under drifting conditions. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating an embodiment of the vehicle drift control method of this application; Figure 2 This is a functional module diagram of an embodiment of the vehicle drift control system of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application are described below with reference to the accompanying drawings and related embodiments. In the description of the embodiments of this application, the terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to be a limitation of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise.

[0021] It should also be understood that in the following embodiments of this application, "at least one" and "one or more" refer to one or more (including two). The term "and / or" is used to describe the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0022] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. The term "connection" includes direct connections and indirect connections, unless otherwise stated. "First" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0023] In the embodiments of this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0024] The steps involved in the methods provided in this application are merely examples, and not all steps are mandatory, nor are all information or message contents required. They can be added or removed as needed during use. In this application, the same step, or steps or messages with the same function, can be referenced and learned from each other in different embodiments.

[0025] The vehicle drift control method provided in this application can be applied to vehicles with four-wheel independent drive. Four-wheel independent drive means that each of the vehicle's four wheels is driven by an independent motor, allowing for precise control of the torque of each wheel individually. In the prior art, vehicle stability control systems primarily aim to suppress sideslip, which can over-intervene and cause drift interruption during drifting; while fully automated drift control deprives the driver of a sense of participation. To address the technical problem that traditional stability control cannot balance the fun and controllability of drifting, this application provides a vehicle drift control method. In this method, the control system can calculate the vehicle's drift equilibrium point state, provide the driver with steering wheel angle guidance, and dynamically distribute torque to the four wheels using model predictive control, ensuring that the vehicle can perform drifting maneuvers without losing control.

[0026] The vehicle in this application embodiment can be a new energy vehicle equipped with four independent drive motors, such as a sedan, SUV, or sports car. The control system in this application embodiment can also be referred to as a vehicle control unit or a drift control domain controller.

[0027] The vehicle drift control system may include a processor, memory, sensor modules, a human-machine interface module, and a motor drive module. The sensor modules may include wheel speed sensors, steering wheel angle sensors, inertial measurement units, and vehicle speed sensors. The human-machine interface module may include a display screen and an audio system. The motor drive module may include a left front motor, a right front motor, a left rear motor, a right rear motor, and their corresponding motor controllers.

[0028] The processor may include one or more processing units, such as application processors, microcontrollers, digital signal processors, etc. Different processing units may be independent devices or integrated into one or more processors. The processor may also include memory for storing instructions and data. The memory can also be used to store computer programs. In the vehicle drift control method provided in this application embodiment, the actions of the control system can be executed by the processor in the control system calling the computer program stored in the memory.

[0029] The sensor module is used to collect real-time operating status signals of the vehicle. Wheel speed sensors detect the rotational speeds of the four wheels; steering wheel angle sensors detect the actual steering wheel angle turned by the driver; the inertial measurement unit detects the vehicle's yaw rate, longitudinal acceleration, and lateral acceleration; and the vehicle speed sensor detects the vehicle's real-time speed. This data forms the basis for subsequent calculations of the drift equilibrium point and torque distribution.

[0030] The human-machine interface module facilitates information exchange between the driver and the control system. The display screen can show guidance information on the target front wheel steering angle corresponding to the drift balance point, such as through reference lines, a virtual steering wheel, or color cues. The audio system can play voice prompts.

[0031] The motor drive module is used to execute torque commands issued by the control system. The four independent drive motors can each receive independent torque commands to generate the required yaw moment and longitudinal driving force to maintain the vehicle's steady-state drift process.

[0032] It is understood that the interface connection relationships between the modules illustrated in the embodiments of this application are merely illustrative and do not constitute a specific limitation on the vehicle control system. In other embodiments of this application, the control system may also employ different interface connection methods or a combination of multiple interface connection methods as described in the above embodiments.

[0033] The following section uses a vehicle control system as an example, and describes in detail the vehicle drift control method provided in the embodiments of this application, in conjunction with the accompanying drawings and specific application scenarios.

[0034] In one possible implementation, see Figure 1 The vehicle drift control method provided in this application embodiment may include the following steps S10 to S50, and the executing entity of this method is a vehicle control system with four-wheel independent drive function. The specific steps in this method are as follows: S10: Based on the obtained tire force of the target vehicle, the state data of the target vehicle, and the preset state variable balance equation set, obtain the front wheel steering angle balance point, the center of gravity sideslip angle balance point, and the yaw rate balance point of the target vehicle.

[0035] The target vehicle's state data includes the resultant tire force on the X-axis, the resultant tire force on the Y-axis, vehicle mass, sideslip angle, front axle center-of-gravity distance, rear axle center-of-gravity distance, wheel moment of inertia, and real-time vehicle speed. The drift equilibrium point refers to the ideal motion state point where the vehicle's sideslip angle, yaw rate, and other state variables remain relatively stable (i.e., their derivatives are zero) during drifting. The sideslip angle is the angle between the vehicle's center-of-gravity velocity direction and the vehicle's longitudinal axis, a key indicator for measuring the drift amplitude. Yaw rate is the angular velocity of the vehicle rotating about its vertical axis. Based on a three-degree-of-freedom vehicle dynamics model, the system uses the real-time vehicle speed as input to solve a system of nonlinear equations to obtain the target front wheel steering angle, target sideslip angle, and target yaw rate required to maintain steady-state drift at the current vehicle speed.

[0036] This embodiment mainly focuses on the detailed calculation process of the tire force of the target vehicle obtained in step S10 and the solution of the equilibrium point. Accurate estimation of tire force is the foundation of drift control, especially in the nonlinear region where tire force saturation occurs.

[0037] In some embodiments, the control system first calculates the resultant force based on the vehicle's longitudinal and lateral dynamics equations. The vehicle's longitudinal dynamics equation is: (1) The vehicle's lateral dynamics equations are: (2) in, For vehicle quality, and Indicates the velocity components in the x and y directions. for and The corresponding derivative, where r is the vehicle's yaw rate. This represents the resultant force along the X and Y axes.

[0038] Furthermore, the control system calculates based on the tire force composition equation. and The equation for the resultant force along the X-axis is: (3) The equation for the resultant force along the Y-axis is: (4) in, and These represent the longitudinal and lateral forces of each wheel, respectively. The subscripts ij indicate fl (left front wheel), fr (right front wheel), rl (left rear wheel), and rr (right rear wheel). Indicates the front wheel steering angle.

[0039] The control system calculates the vehicle state based on the relationship between speed and sideslip angle. The longitudinal speed component is: (5) The lateral velocity component is: (6) The vehicle's center of gravity speed is: (7) Differentiate with respect to time: (8) Substituting (1) and (2) into equations, we get: (9) The centroid sideslip angle is: (10) The derivative of the centroid side deflection angle is: (11) Where V is the velocity of the vehicle's center of gravity. Let β be the derivative of the vehicle's center of gravity velocity, and β be the vehicle's center of gravity sideslip angle. The derivative of the centroid sideslip angle; Substituting equations (1), (2), (5), and (6) yields: (12) The control system is based on the yaw dynamics equation: Calculate the yaw moment, which is: (13) get: (14) in, The yaw moment about the vehicle's center of mass, and These represent the distance between the front axle center of gravity and the distance between the rear axle center of gravity, respectively. It is the moment of inertia of the wheel. This is the yaw acceleration.

[0040] For the specific set of equations used to obtain the equilibrium point in step S10, the preset state variable equilibrium equation set includes a first state variable equilibrium equation set, a second state variable equilibrium equation set, and a third state variable equilibrium equation set, which correspond to the longitudinal lateral motion, yaw motion, and torque balance of the vehicle, respectively. At the drift equilibrium point, the derivatives of the state variables are zero, and the equilibrium point equation set is: (15) According to equilibrium point theory, the derivative of the state variables of the system is 0 at the equilibrium point. Let the equilibrium point be: (16) Then the front wheel steering angle balance point Center of mass side slip angle equilibrium point Equilibrium point of yaw rate : (17) To solve the equilibrium equations, the tire model must first be determined to obtain the tire forces. The Fiala tire model, based on the friction circle theory, is used to calculate the tire forces. The friction circle theory states that the sum of the squares of the lateral and longitudinal forces of the tire will not exceed an elliptical boundary, as expressed in the following formula: (18) Where 'i' represents one of the four wheels. The pre-set road surface adhesion coefficient (e.g., 0.8) is used. These represent the longitudinal force, lateral force, and four-wheel load, respectively. Equality is assumed when the tire force is saturated. Drifting occurs when the rear tires are fully saturated and the front tires are nearly saturated; therefore, equality can be assumed in this case. (19) Lateral forces were calculated using the Fiala tire model: (20) in, The tire slip angle is calculated using the following formula, where C is the tire slip stiffness, i is the tire slip angle, f represents the front wheel, and r represents the rear wheel.

[0041] (twenty one) in, These represent the longitudinal forces at the tire slip angles of the front and rear axles, respectively. This refers to the load on all four wheels, meaning the vehicle's weight is evenly distributed across all four wheels. The subscript 'i' indicates the wheel number. (twenty two) Meanwhile, the vehicle speed changes very little in a very short time and can be considered a constant parameter obtained from sensors. At this point, only the sideslip angle of the center of mass remains in the equilibrium equation. yaw rate Front wheel steering angle The unknown quantity is 'I,' and all others are known quantities. The equilibrium point can then be determined from these unknown quantities. (twenty three).

[0042] S20, obtains the actual center of gravity sideslip angle after the driver and passengers operate based on the front wheel steering angle balance point.

[0043] In this step, the front wheel steering angle equilibrium point calculated in step S10 is converted into a guidance signal to prompt the driver to operate. After the driver turns the steering wheel according to the guidance, the vehicle state changes. The system estimates the current actual center of gravity sideslip angle through a vehicle state observer combined with sensor data. The vehicle state observer can be a Kalman filter, used to estimate unmeasurable signals using measurable signals, providing feedback for closed-loop control.

[0044] This embodiment mainly focuses on the specific implementation of human-machine collaboration in step S20, which includes generating guidance signals, collecting operation data, and observing the status.

[0045] In some embodiments, the control system generates a target steering wheel angle based on the front wheel steering angle equilibrium point. Specifically, this can be converted using the vehicle's steering gear ratio, as shown in the formula: (twenty four) in, For the front wheel steering angle, For the target steering wheel angle, This refers to the vehicle's steering gear ratio parameter. The system will... The information sent to the display screen of the human-machine interface module is presented to the driver in the form of visual reference lines, a virtual steering wheel, or color prompts, or guided by the torque applied through the electric power steering system.

[0046] For example, assuming the calculated target steering wheel angle is a specific angle, after the user activates drift mode, the control system can display a guidance interface on the screen. This interface displays instruction information, including the target steering angle indicator and the actual steering angle indicator. The steering guidance diagram can be a pie chart, where the central angle indicates the angle range corresponding to the target steering wheel angle. If the driver's actual steering angle is not aligned with the arc area of ​​the guidance diagram, it indicates that the current steering angle does not meet the drift balance point requirements; if the driver's actual steering angle is aligned with the arc area of ​​the guidance diagram, it indicates that the current steering angle meets the requirements.

[0047] Optionally, if the steering angle does not meet the requirements, the control system can also display guidance information to guide the user to adjust the direction of the steering wheel so that the actual steering angle is aligned with the target steering angle. For example, the guidance information can be an arrow or text; if the target steering angle is to the right of the actual steering angle, the guidance information can be a right arrow to guide the user to turn the steering wheel to the right.

[0048] The control system acquires the actual steering wheel angle, real-time vehicle speed, and yaw rate when the driver and passengers operate the steering wheel. This data is collected in real time by a steering wheel angle sensor, wheel speed sensor, and inertial measurement unit. Based on the actual steering wheel angle, real-time vehicle speed, yaw rate, and the acquired vehicle mass and vehicle state observer, the actual center of gravity sideslip angle is obtained.

[0049] S30: Based on the actual center of mass sideslip angle, center of mass sideslip angle equilibrium point, preset center of mass sideslip angle error feedback gain, preset yaw rate gain, and yaw rate equilibrium point, the target yaw torque is obtained.

[0050] The system employs a nested inner and outer loop control strategy. The outer loop corrects the desired yaw rate based on the error in the sideslip angle at the center of gravity, while the inner loop calculates the torque required to maintain this state based on the error in the yaw rate. The target yaw torque refers to the total torque around the vehicle's center of gravity that the control system needs to apply to maintain steady-state drift.

[0051] This embodiment mainly focuses on the control logic for obtaining the target yaw moment in step S30, and adopts an inner and outer loop nested control strategy.

[0052] In some embodiments, the control system obtains the desired yaw rate according to the outer-loop control formula. The outer-loop control formula is: (25) in, Let yaw rate be the angular velocity at a certain drift equilibrium point. For the centroid sideslip angle error feedback gain, The sideslip angle is the angle of the centroid. The equilibrium point of the centroid's sideslip angle. Desired yaw rate. Due to steady-state drift. The system eliminates sideslip angle error by adjusting the desired yaw rate.

[0053] The control system obtains the desired yaw rate based on the inner-loop control formula, which is: (26) in, For the desired yaw rate, To preset the yaw rate gain, The current yaw rate, The derivative of the yaw rate. For the desired yaw rate, Let be the derivative of the desired yaw rate.

[0054] The control system is based on the target yaw moment formula. The target yaw moment is obtained by the following formula: (27) During drift, the yaw rate is generally in a stable state with small fluctuations, so for ease of calculation, we take... The final target yaw moment is then obtained as follows: (28) in, The target yaw moment is the total yaw moment target required to maintain stable drifting of the vehicle. In this process, the system obtains the expected yaw rate balance point (i.e. expected yaw rate related terms) based on the difference between the current yaw rate and the expected yaw rate of the target vehicle, the preset yaw rate gain, and the yaw rate balance point. Then, based on the obtained wheel moment of inertia, the expected yaw rate balance point, the preset yaw rate gain, and the difference between the yaw rate and the expected yaw rate, the target yaw moment is obtained.

[0055] S40, construct the objective function based on the obtained slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment.

[0056] Here, slip ratio refers to the ratio of the longitudinal slip velocity of the wheel to the velocity at the wheel center, reflecting the degree of wheel slippage. Model predictive control is a multivariable constrained control algorithm that solves the optimization problem online by predicting the vehicle's state over a future period. To accurately control the vehicle under extreme conditions, the system introduces model predictive control. The objective function aims to minimize the deviation between the actual yaw moment and the target yaw moment, as well as the deviation between the actual slip ratio and the target slip ratio, over a future period.

[0057] S50 obtains the four-wheel execution torque based on the objective function and model predictive control algorithm to achieve vehicle drift control.

[0058] Under the premise of satisfying the physical constraints of the motors, the system performs rolling optimization to solve the objective function, obtains the optimal four-wheel torque distribution sequence, and sends the first control variable in the sequence to the motor controller for execution. The four-wheel execution torque refers to the specific torque command allocated to the four independent drive motors.

[0059] This embodiment mainly focuses on the specific implementation of model predictive control in steps S40 and S50. The method includes state prediction, construction of objective function and rolling optimization solution.

[0060] In some embodiments, the control system performs state prediction. Regarding slip ratio prediction, the current slip ratio is obtained by matching a preset two-dimensional lookup table, real-time vehicle speed, and actual center of gravity sideslip angle. The target slip ratio formula is: (29) in, The function is implemented using a pre-defined two-dimensional lookup table to determine the target wheel slip ratio. The lookup table is in the following form:

[0061] The control system obtains the state at the next moment based on the wheel speed and slip ratio prediction formula. The wheel speed formula at the next moment is: (30) The formula for the slip ratio at the next moment is: (31) in, The angular velocity of the wheel. The tire's rolling radius, For wheel drive torque, For the moment of inertia of the wheel, To control the cycle, and These represent the current time and the next control time, respectively.

[0062] For yaw moment prediction, the yaw moment at the next moment is obtained based on the obtained left wheel track, right wheel track, tire rolling radius, and the difference in driving torque of each wheel. The formula is as follows: (32) Where d is the wheelbase determined based on the left and right wheelbases. This is the yaw moment at the next moment.

[0063] The control system constructs tracking terms based on the difference between the target yaw moment and the yaw moment at the next moment, and the difference between the slip ratio and the slip ratio at the next moment. These tracking terms are then weighted and combined to obtain the objective function. The objective optimization function is: (33) in, For the objective function cost, Indicates the current moment. Indicates the next control moment. To track the yaw moment weight, For slip ratio tracking weights, preset weight coefficients are used to balance the priority of yaw stability and slip ratio control; Substituting formulas (30), (31), and (32) into the objective function (33), we get: (34).

[0064] The control system obtains preset four-wheel torque constraints, which are that the torque of all four wheels is less than or equal to the first preset torque limit, and the torque of all four wheels is greater than or equal to the second preset torque limit. The formula is as follows:

[0065] in, The first preset torque limit, For the second preset torque limit, the objective function is solved by rolling optimization based on the model predictive control algorithm and the preset four-wheel torque constraints to obtain the control sequence. The rolling optimization process includes calculating the yaw moment corresponding to the four wheel torques at the next moment and minimizing the deviation between the yaw moment at the next moment and the target yaw moment. The first control quantity in the control sequence is decomposed into independent torque commands for the four wheels, thus obtaining the four-wheel execution torque.

[0066] Based on the method provided in the above embodiments of this application, the control system can display indication information to indicate the relative position of the target turning angle and the actual turning angle based on the calculated drift balance point. In the case of misalignment, the displayed guidance information can guide the user to adjust the direction of the steering wheel, thereby improving the drift stability of the vehicle and enabling the vehicle's state to meet the requirements of drift control. This solves the problem of vehicle loss of control or drift interruption caused by improper control strategy.

[0067] The method embodiments provided by this application have been described above. The apparatus embodiments provided by this application will be described below. It should be understood that the description of the apparatus embodiments corresponds to the description of the method embodiments. Therefore, any content not described in detail can be referred to the method embodiments above. For the sake of brevity, it will not be repeated here.

[0068] See Figure 2 This application provides a vehicle drift control system. The system can be a module or chip applied to a vehicle. The system can be used to execute the steps or processes performed by the control system in the above embodiments.

[0069] The system may include a balance point calculation module, a steering operation module, a torque determination module, an objective function construction module, and a torque distribution module. The balance point calculation module is used to obtain the front wheel steering angle balance point, center of gravity sideslip angle balance point, and yaw rate balance point of the target vehicle based on the acquired tire forces, target vehicle state data, and a preset set of state variable balance equations.

[0070] The steering operation module acquires the actual sideslip angle after the driver / passenger operates based on the front wheel steering angle balance point. The torque determination module calculates the target yaw moment based on the actual sideslip angle, sideslip angle balance point, preset sideslip angle error feedback gain, preset yaw rate gain, and yaw rate balance point. The objective function construction module constructs an objective function based on the acquired slip ratio, next-moment slip ratio, target yaw moment, and next-moment yaw moment. The torque distribution module calculates the four-wheel torque based on the objective function and the model predictive control algorithm to achieve vehicle drift control.

[0071] It should be understood that the description of the system embodiments can refer to the relevant descriptions of the various method embodiments above. The implementation principle and technical effect are similar to those of the method embodiments above, and will not be repeated here.

[0072] It should be understood that modules in a system can be implemented in hardware, software, or by hardware executing corresponding software. For example, a module can refer to application-specific integrated circuits, electronic circuits, processors and memory for executing one or more software or firmware programs, integrated logic circuits, and / or other suitable components that support the described functions.

[0073] Based on the methods provided in the above embodiments, this application also provides the following: This application provides a vehicle drift control device, which includes a processor, a memory, and a vehicle drift control program stored in the memory and executable by the processor. When the vehicle drift control program is executed by the processor, it implements the steps of the vehicle drift control method as described in any of the above method embodiments.

[0074] This application provides a computer-readable storage medium storing a vehicle drift control program, wherein when the vehicle drift control program is executed by a processor, it implements the steps of the vehicle drift control method as described in any of the above method embodiments.

[0075] This application provides a chip including a memory and a processor. The processor executes a computer program stored in the memory to implement the vehicle drift control method shown in the above embodiments.

[0076] It should be understood that the processor mentioned in the embodiments of this application can be a central processing unit, or it can be other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0077] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory can be read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, or flash memory. Volatile memory can be random access memory used as an external cache. By way of example, but not limitation, many forms of random access memory are available, such as static random access memory, dynamic random access memory, synchronous dynamic random access memory, double data rate synchronous dynamic random access memory, enhanced synchronous dynamic random access memory, synchronously linked dynamic random access memory, and direct memory bus random access memory.

[0078] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. In the above embodiments, the descriptions of each embodiment have different focuses; parts not described in detail or recorded in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0079] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0080] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0081] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0082] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0083] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0084] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0085] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0086] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for controlling vehicle drift, characterized in that, The vehicle drift control method includes: Based on the obtained tire force of the target vehicle, the state data of the target vehicle, and the preset state variable balance equation set, the front wheel steering angle balance point, the center of gravity sideslip angle balance point, and the yaw rate balance point of the target vehicle are obtained. Obtain the actual center of gravity sideslip angle after the driver and passengers operate based on the front wheel steering angle balance point; The target yaw torque is obtained based on the actual centroid sideslip angle, the centroid sideslip angle equilibrium point, the preset centroid sideslip angle error feedback gain, the preset yaw rate gain, and the yaw rate equilibrium point. Construct an objective function based on the obtained slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment; Based on the objective function and model predictive control algorithm, the four-wheel execution torque is obtained to achieve vehicle drift control.

2. The vehicle drift control method according to claim 1, characterized in that, The obtained tire force of the target vehicle includes: Based on the obtained distance between the front axle center of gravity and the rear axle center of gravity, the tire slip angle of the front axle and the tire slip angle of the rear axle are obtained. Based on the obtained vehicle weight and vehicle mass, determine the load on each tire; Based on the tire slip angle of the front axle, the tire slip angle of the rear axle, and each tire load, as well as the obtained tire lateral stiffness, preset road adhesion coefficient, and preset Fiala tire model, the tire lateral force is determined. The longitudinal force of the tire is calculated based on the tire lateral force and the pre-set tire mechanics formula; The tire force is obtained by vector synthesis of the tire lateral force and the tire longitudinal force.

3. The vehicle drift control method according to claim 1, characterized in that, The step of obtaining the front wheel steering angle balance point, center of gravity sideslip angle balance point, and yaw rate balance point of the target vehicle based on the acquired tire forces, target vehicle state data, and preset state variable balance equations includes: Acquire the state data of the target vehicle, which includes the tire resultant force on the X-axis, the tire resultant force on the Y-axis, the vehicle mass, the sideslip angle, the distance between the front axle and the rear axle, the wheel moment of inertia, and the real-time vehicle speed. The pre-set state variable equilibrium equation set includes the first state variable equilibrium equation set, the second state variable equilibrium equation set, and the third state variable equilibrium equation set; Based on the obtained tire net force on the X-axis, tire net force on the Y-axis, vehicle mass, real-time vehicle speed, center of gravity sideslip angle, and the first state variable balance equation set of the target vehicle, the center of gravity sideslip angle equilibrium point is obtained. Based on the obtained tire net force on the X-axis, tire net force on the Y-axis, vehicle mass, real-time vehicle speed, the center of gravity sideslip angle equilibrium point, and the second state variable equilibrium equation set, the yaw rate equilibrium point is obtained. Based on the obtained tire force, front axle center of mass distance, rear axle center of mass distance, wheel moment of inertia, and the third state variable balance equations of the target vehicle, the front wheel steering angle equilibrium point is obtained.

4. The vehicle drift control method according to claim 1, characterized in that, The acquisition of the actual sideslip angle of the center of gravity after the driver and passengers operate based on the front wheel steering angle balance point includes: A target steering wheel angle is generated based on the front wheel steering angle balance point, so that the driver and passengers can operate the steering wheel based on the target steering wheel angle; Acquire the actual steering wheel angle, real-time vehicle speed, and yaw rate when the driver and passengers are operating the steering wheel; The actual center of gravity sideslip angle is obtained based on the actual steering wheel angle, the real-time vehicle speed, the yaw rate, the acquired vehicle mass, and the vehicle state observer.

5. The vehicle drift control method according to claim 1, characterized in that, The step of obtaining the target yaw moment based on the actual sideslip angle, the sideslip angle equilibrium point, the preset sideslip angle error feedback gain, the preset yaw rate gain, and the yaw rate equilibrium point includes: Based on the difference between the actual centroid sideslip angle and the centroid sideslip angle equilibrium point, as well as the obtained preset centroid sideslip angle error feedback gain and the yaw rate equilibrium point, the desired yaw rate is obtained. The target yaw torque is obtained based on the desired yaw rate, the preset yaw rate gain, and the yaw rate equilibrium point.

6. The vehicle drift control method according to claim 5, characterized in that, The step of obtaining the target yaw torque based on the desired yaw rate, the preset yaw rate gain, and the yaw rate equilibrium point includes: The desired yaw rate equilibrium point is obtained by the difference between the current yaw rate of the target vehicle and the desired yaw rate, the preset yaw rate gain, and the yaw rate equilibrium point. The target yaw torque is obtained based on the acquired wheel moment of inertia, the desired yaw rate equilibrium point, the preset yaw rate gain, and the difference between the yaw rate and the desired yaw rate.

7. The vehicle drift control method according to claim 1, characterized in that, The step of constructing the objective function based on the obtained slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment includes: The current slip ratio is obtained by matching the preset two-dimensional lookup table, real-time vehicle speed and actual center of gravity sideslip angle. The wheel speed at the next moment is obtained based on the current wheel speed, the wheel moment of inertia within the preset control cycle, the tire longitudinal force, the tire rolling radius, and the current torque. The slip ratio at the next moment is obtained based on the component of the wheel speed and the vehicle center of gravity speed in the tire plane direction at the next moment. Based on the obtained left wheel track, right wheel track, tire rolling radius, and the difference in driving torque of each wheel, the yaw moment at the next moment is obtained; Based on the difference between the target yaw moment and the yaw moment at the next moment, and the difference between the slip ratio and the slip ratio at the next moment, a tracking term is constructed. The tracking terms are then weighted and combined to obtain the objective function.

8. The vehicle drift control method according to claim 7, characterized in that, The step involves constructing tracking terms based on the difference between the target yaw moment and the yaw moment at the next moment, and the difference between the slip ratio and the slip ratio at the next moment. A weighted combination of these tracking terms yields the objective function, including: The difference between the target yaw moment and the yaw moment at the next moment is calculated to obtain the yaw moment tracking term; The difference between the obtained slip ratio and the slip ratio at the next moment is calculated to obtain the slip ratio tracking term; The objective function is obtained based on the yaw moment tracking term, the slip ratio tracking term, and the obtained preset weight coefficients.

9. The vehicle drift control method according to claim 1, characterized in that, The step of obtaining the four-wheel execution torque based on the objective function and model predictive control algorithm to achieve vehicle drift control includes: Obtain preset four-wheel torque constraint conditions, wherein the four-wheel execution torque is less than or equal to a first preset torque limit value, and the four-wheel execution torque is greater than or equal to a second preset torque limit value; The objective function is solved by rolling optimization based on the model predictive control algorithm and the preset four-wheel torque constraints to obtain the control sequence. The rolling optimization solution process includes calculating the yaw moment corresponding to the torque of the four wheels at the next moment, and minimizing the deviation between the yaw moment at the next moment and the target yaw moment; The first control quantity in the control sequence is decomposed into independent torque commands for the four wheels, thereby obtaining the four-wheel execution torque.

10. A vehicle drift control system, characterized in that, The system includes: The equilibrium point calculation module is used to obtain the front wheel steering angle equilibrium point, center of gravity sideslip angle equilibrium point, and yaw rate equilibrium point of the target vehicle based on the obtained tire force of the target vehicle, the state data of the target vehicle, and the preset state variable equilibrium equation set. The steering operation module is used to obtain the actual center of gravity sideslip angle after the driver and passengers operate based on the front wheel steering angle balance point; The torque determination module is used to obtain the target yaw torque based on the actual center of mass sideslip angle, the center of mass sideslip angle equilibrium point, the preset center of mass sideslip angle error feedback gain, the preset yaw rate gain, and the yaw rate equilibrium point. The objective function construction module is used to construct an objective function based on the obtained slip ratio, the slip ratio at the next moment, the target yaw moment, and the yaw moment at the next moment. The torque distribution module is used to obtain the four-wheel execution torque according to the objective function and the model predictive control algorithm to achieve vehicle drift control.

11. A vehicle drift control device, characterized in that, The vehicle drift control device includes a processor, a memory, and a vehicle drift control program stored in the memory and executable by the processor, wherein when the vehicle drift control program is executed by the processor, it implements the steps of the vehicle drift control method as described in any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a vehicle drift control program, wherein when the vehicle drift control program is executed by a processor, it implements the steps of the vehicle drift control method as described in any one of claims 1 to 9.

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