Coordinated control method and apparatus for lateral stability of electric vehicle and storage medium

Abstract

A coordinated control method and apparatus for the lateral stability of an electric vehicle and a storage medium. The method comprises: acquiring the current yaw velocity, the current sideslip angle, the current longitudinal velocity and a steering angle input by a driver; on the basis of the current yaw velocity, the current sideslip angle, the current longitudinal velocity and the steering angle, using a preset hybrid control rule to determine an additional yaw moment and an additional front wheel steering angle; sending the additional yaw moment to a DYC system, so that the DYC system allocates the additional yaw moment on the basis of a preset allocation rule, so as to obtain respective longitudinal braking forces of four hubs; and sending the additional front wheel steering angle to an AFWS system, so that the AFWS system allocates the additional front wheel steering angle on the basis of a preset steering control rule, so as to obtain respective steering angles of the four hubs. The present application avoids a lack of driving comfort and stability during single-system yaw control, ultimately remarkably improving the lateral control stability of vehicles.

Description

Methods, devices and storage media for coordinated control of lateral stability of electric vehicles Cross-references to related applications

[0001] This application claims priority to Chinese patent application No. 202410555378.1, filed on May 7, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of collaborative control technology for vehicle stability, and more specifically, to a method, apparatus, storage medium, and electric vehicle for collaborative control of lateral stability. Background Technology

[0003] With the significant increase in demand for low-carbon transportation, all-electric vehicles (EVs) have attracted widespread attention. Due to their advantages of rapid response, high precision, and flexible maneuverability, research on four-wheel independent drive electric vehicles (FWID-EVs) is intensifying. However, these vehicles face challenges in terms of lateral stability, requiring coordination of distributed in-vehicle motors and other actuators. Furthermore, active stability control systems, such as Direct Yaw Moment Control (DYC), play a crucial role in improving vehicle dynamics. However, due to the strong coupling characteristics of the vehicle chassis, different subsystems such as AFWS (Active Front Wheel Steering System) and DYC may interact when operating simultaneously. Therefore, chassis-coordinated control of multiple subsystems is of significant design importance for improving vehicle stability.

[0004] Currently, lateral stability cooperative control technologies for electric vehicles mainly include the following: For example, some technologies have designed a robust fault-tolerant control method for the lateral stability of autonomous electric vehicles. This method establishes a lateral dynamic fault-tolerant control system model for autonomous electric vehicles by collecting inherent and real-time parameters of the electric vehicle. It analyzes tire nonlinearity, changes in the vehicle's current longitudinal speed, and the adaptive triggering mechanism, and establishes a comprehensive control system model. Finally, a robust fault-tolerant controller is designed to distribute the yaw moment of the vehicle, achieving effective control of the vehicle's nonlinear dynamics system and improving lateral stability. Another related technology designs a lateral stability controller based on FASMC, which uses modeling methods to solve for the additional yaw moment required when the vehicle is turning, and designs a lower-level controller to obtain the additional direct yaw moment of each module and distribute it to the actuators, ultimately effectively improving the vehicle's lateral stability. However, chassis coordinated control involves multiple subsystems and complex control and adjustment problems, requiring solutions for the coordinated work between multiple interactive subsystems. This increases the complexity of system design and adjustment. Furthermore, some controllers (such as DYC and AFWS) have large control authority in certain nonlinear regions, leading to a lack of flexibility and robustness under specific conditions. Furthermore, current technologies fail to adequately consider the dynamic characteristics of vehicle subsystems, potentially leading to poor performance in responding to dynamic changes. Overall, existing technologies have limitations in terms of flexibility in control authority allocation, adaptability to dynamic situations, and complexity.

[0005] Therefore, existing technologies suffer from a lack of coordination among multiple subsystems in chassis coordination control, resulting in poor performance of electric vehicles when dealing with dynamic changes, leading to a lack of driving comfort and stability. Summary of the Invention

[0006] This application provides a method for coordinated lateral stability control of electric vehicles to address the lack of coordination among multiple subsystems in chassis coordinated control in existing technologies. By using a preset hybrid control rule based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and driver-input steering angle, an additional yaw torque and an additional front wheel steering angle are determined. The additional yaw torque is then distributed to the hub motors of the four wheel hubs via the DYC system, which outputs braking force respectively. Similarly, the additional front wheel steering angle is distributed to the steering motors of the four wheel hubs via the AWFS system, which outputs steering angle respectively. This achieves coordinated operation of the DYC system and the AWFS system on the electric vehicle chassis, avoiding the lack of driving comfort and stability when a single system performs yaw control, and ultimately significantly improving the stability of vehicle lateral control.

[0007] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0008] In a first aspect, this application provides a method for coordinated lateral stability control of electric vehicles, applied to a vehicle control unit, the method comprising:

[0009] Obtain the electric vehicle's current yaw rate, current sideslip angle, and current longitudinal velocity, as well as the steering angle input by the driver;

[0010] The additional yaw moment and additional front wheel steering angle are determined based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed and steering angle using a preset hybrid control rule;

[0011] The additional yaw moment is sent to the DYC system, which then distributes the additional yaw moment based on a preset distribution rule, thereby obtaining the longitudinal braking force of each of the four wheel hubs of the electric vehicle.

[0012] The additional front wheel steering angle is sent to the AFWS system, which then allocates the additional front wheel steering angle based on preset steering control rules, thus obtaining the steering angles of the four wheel hubs of the electric vehicle.

[0013] Optionally, according to the electric vehicle lateral stability cooperative control method provided in this application, an additional yaw moment and an additional front wheel steering angle are determined based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and steering angle using a preset hybrid control rule, specifically including:

[0014] If the current yaw rate and the current sideslip angle of the center of gravity meet the first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current sideslip angle of the center of gravity, the current longitudinal speed and the steering angle.

[0015] If the current yaw rate and the current sideslip angle of the center of gravity meet the second preset condition, then the additional yaw torque and the additional front wheel steering angle are determined by a preset hybrid control algorithm based on the current yaw rate, the current sideslip angle of the center of gravity, the current longitudinal speed and the steering angle.

[0016] Optionally, according to the electric vehicle lateral stability cooperative control method provided in this application, if the current yaw rate and the current sideslip angle meet a first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current sideslip angle, the current longitudinal speed, and the steering angle; if the current yaw rate and the current sideslip angle meet a second preset condition, then the additional yaw torque and the additional front wheel steering angle are determined using a preset hybrid control algorithm based on the current yaw rate, the current sideslip angle, the current longitudinal speed, and the steering angle, specifically including:

[0017] The first cost function of the DYC system and the second cost function of the AFWS system are determined based on the current yaw rate, current centroid sideslip angle, current longitudinal speed and steering angle. The first cost function includes the additional yaw moment to be determined and the corresponding moment weighting coefficient, and the second cost function includes the additional front wheel steering angle to be determined and the corresponding angle weighting coefficient.

[0018] Determine the current hazard factor based on the current yaw rate and the current sideslip angle of the center of gravity;

[0019] If the current risk factor is less than the preset threshold, the torque weighting coefficient and the angle weighting coefficient are set to the first weighting combination;

[0020] If the current risk factor is greater than the preset threshold, the torque weighting coefficient and the angle weighting coefficient are set to the second weighting combination, which is determined based on the current risk factor.

[0021] The coordinated control rule based on the Stackelberg equilibrium strategy constructs an optimization problem for the first cost function and the second cost function. Based on the optimal solution of the optimization problem, the additional front wheel steering angle and additional yaw moment are determined. The additional yaw moment determined by the optimal solution of the corresponding optimization problem constructed using the first weight combination is zero.

[0022] Optionally, according to the electric vehicle lateral stability cooperative control method provided in this application, a first cost function of the DYC system and a second cost function of the AFWS system are determined based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal velocity, and the steering angle. The first cost function includes an additional yaw moment to be determined and the corresponding moment weighting coefficient, and the second cost function includes an additional front wheel steering angle to be determined and the corresponding angle weighting coefficient. Specifically, it includes:

[0023] The state error equation is determined based on the current yaw rate, current centroid sideslip angle, current longitudinal velocity, and steering angle.

[0024] The first cost function of the DYC system is determined based on the state error equation, the additional yaw moment to be determined, and the corresponding moment weighting coefficient.

[0025] The second cost function of the AFWS system is determined based on the state error equation, the undetermined additional front wheel steering angle, and the corresponding angle weighting coefficient.

[0026] Optionally, according to the electric vehicle lateral stability cooperative control method provided in this application, the first cost function and the second cost function are optimized using a coordinated control rule based on the Stackelberg equilibrium strategy to determine the additional front wheel steering angle and the additional yaw moment, specifically including:

[0027] The optimization objective is to minimize the value of the second cost function, thereby obtaining the corresponding additional front wheel steering angle.

[0028] The optimization objective is to minimize the value of the first cost function, and the corresponding initial additional yaw moment is obtained.

[0029] The additional yaw moment is determined based on the initial additional yaw moment and the additional front wheel steering angle.

[0030] Optionally, according to the electric vehicle lateral stability cooperative control method provided in this application, the preset allocation rule is to take the minimum sum of tire utilization rates corresponding to the four wheel hubs as the optimization objective, and under preset constraints, determine the braking force of the corresponding four wheel hubs respectively.

[0031] Optionally, according to the electric vehicle lateral stability cooperative control method provided in this application, the preset steering control rule is to determine that the additional steering angles of the two wheel hubs on the front axle are both additional front wheel steering angles, and to determine that the additional steering angles of the two wheel hubs on the rear axle are both additional front wheel steering angles multiplied by a preset ratio.

[0032] Secondly, this application provides a lateral stability cooperative control device for electric vehicles, the device comprising:

[0033] The acquisition unit is used to acquire the electric vehicle's current yaw rate, current center of gravity sideslip angle, and current longitudinal speed, as well as the steering angle input by the driver;

[0034] The determination unit is used to determine the additional yaw moment and the additional front wheel steering angle based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle using a preset hybrid control rule;

[0035] The first transmitting unit is used to transmit the additional yaw torque to the DYC system, so that the DYC system can distribute the additional yaw torque according to the preset distribution rules, thereby obtaining the longitudinal braking force of the four wheel hubs of the electric vehicle respectively.

[0036] The second transmitting unit is used to transmit the additional front wheel steering angle to the AFWS system, so that the AFWS system can allocate the additional front wheel steering angle based on the preset steering control rules, thereby obtaining the steering angles of the four wheel hubs of the electric vehicle respectively.

[0037] Thirdly, this application provides a computer-readable storage medium storing at least one piece of program code, which is loaded and executed by a processor to perform the operations performed by the electric vehicle lateral stability cooperative control method of the first aspect.

[0038] Fourthly, this application provides an electric vehicle, which includes one or more processors and one or more memories, wherein at least one piece of program code is stored in the one or more memories, and the at least one piece of program code is loaded and executed by the one or more processors to perform the operations performed by the electric vehicle lateral stability cooperative control method of the first aspect.

[0039] The electric vehicle lateral stability collaborative control method, device, storage medium, and electric vehicle provided in this application determine the additional yaw torque and additional front wheel steering angle by using a preset hybrid control rule based on the current yaw angle, current center of gravity sideslip angle, current longitudinal speed, and driver input steering angle. Then, the additional yaw torque is distributed to the wheel hub motors of the four wheel hubs through the DYC system to output braking force, and the additional front wheel steering angle is distributed to the steering motors of the four wheel hubs through the AWFS system to output steering angle. This realizes the collaborative work of the DYC system and AFWS system on the electric vehicle chassis, avoiding the lack of driving comfort and stability when a single system performs yaw control, and ultimately significantly improving the stability of vehicle lateral control.

[0040] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the technical solutions or the prior art will be briefly introduced below. Obviously, the drawings described below are some technical solutions of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 is a flowchart of the electric vehicle lateral stability cooperative control method of this application;

[0043] Figure 2 is a structural diagram of the electric vehicle lateral stability cooperative controller based on AFWS and DYC provided in this application;

[0044] Figure 3 is a schematic diagram of the structure of the electric vehicle lateral stability cooperative control device provided in this application;

[0045] Figure 4 is a schematic diagram of the physical structure of an electric vehicle according to this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described technical solutions are only a part of the technical solutions of this application, not all of them. Based on the technical solutions of this application, all other technical solutions obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0047] The following description, in conjunction with Figures 1-4, describes the electric vehicle lateral stability collaborative control method, apparatus, and storage device of this application.

[0048] Figure 1 is a flowchart of the electric vehicle lateral stability cooperative control method of this application. As shown in Figure 1, the method of this application includes the following steps:

[0049] Step 110: Obtain the current yaw rate, current center of gravity sideslip angle, and current longitudinal speed of the electric vehicle, as well as the steering angle input by the driver.

[0050] It should be noted here that in order to improve the driving stability of electric vehicles under good path tracking conditions, a variety of active safety control strategies for vehicles have been proposed, such as anti-lock braking systems, electronic stability systems, active front steering systems (AFWS), and direct yaw torque control systems (DYC). Each of these control systems has its own advantages and disadvantages. Although the output of the active front steering system (AFWS) is an additional front wheel steering angle that does not depend on the steering wheel angle, this additional front wheel steering angle can change the lateral force of the vehicle, which is equivalent to providing an additional yaw torque. Therefore, both the AFWS system and the DYC system are essentially systems that apply additional yaw torque to the vehicle body to intervene in vehicle stability.

[0051] Specifically, the vehicle lateral stability cooperative control method provided in this application is mainly applied to situations where the driver initiates a "cornering" action but does not initiate "acceleration" or "braking" actions. That is, the driver only inputs front wheel steering angle information to the vehicle control unit, without accelerator pedal displacement information or brake pedal displacement information. Therefore, this application only considers how to determine and execute the corresponding additional front wheel steering angle and additional yaw moment in response to the driver's "cornering" intention when the vehicle's current speed remains unchanged. Since the purpose of the additional front wheel steering angle and additional yaw moment generated by the vehicle control unit is to intervene in the vehicle stability during cornering, so that the vehicle can keep up with the driver's "cornering" intention and take into account the constraints of the current vehicle driving state, the additional front wheel steering angle and additional yaw moment required to determine the additional vehicle parameters that need to be provided during the vehicle's cornering process must include at least the steering angle input by the driver, the current yaw rate, the current center of gravity sideslip angle, and the current longitudinal speed. Among them, the desired yaw rate and desired center of gravity sideslip angle can be determined based on the steering angle input by the driver through a preset vehicle model. Then, based on the desired yaw rate, desired center of gravity sideslip angle, current yaw rate, current center of gravity sideslip angle, and current longitudinal speed, the additional front wheel steering angle and additional yaw moment that keep the vehicle stable when the current center of gravity sideslip angle tracks the desired center of gravity sideslip angle and the current yaw rate tracks the desired yaw rate can be determined.

[0052] It should also be noted that the electric vehicle's current yaw rate, current center of gravity sideslip angle, and current longitudinal speed are collected by their respective on-board sensors, while the steering angle input by the driver is input through the steering wheel connection component.

[0053] Step 120: Based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed and steering angle, determine the additional yaw moment and additional front wheel steering angle using a preset hybrid control rule.

[0054] Specifically, the additional front wheel steering angle is controlled by the AFWS system, which controls the steering motors corresponding to each wheel hub, while the additional yaw torque is controlled by the DYC system, which controls the drive motors corresponding to each wheel hub. The AFWS system corrects the vehicle's operating state by applying an appropriate additional front wheel steering angle, thus improving steering stability by altering the vehicle's lateral force. However, due to the nonlinear characteristics of the tires, the control effect is limited after the tire lateral force reaches its limit. Therefore, the DYC system needs to further generate additional yaw torque to maintain vehicle steering stability. The DYC system uses driver input signals and vehicle status information to control the difference in braking force between the left and right wheels, generating additional yaw torque to improve stability during cornering. Although the DYC system is unaffected by tire nonlinear characteristics when the AFWS system fails, maintaining good control under extreme conditions—meaning it can still provide effective control even when the vehicle is unstable—the intervention of the DYC system significantly impacts the vehicle's longitudinal movement, causing a decrease in speed and affecting passenger comfort. Therefore, the technical solution of this application adopts a preset hybrid control rule to determine the additional front wheel steering angle to be executed by the AFWS system and the additional yaw torque to be executed by the DYC system. The preset hybrid control rule can fully consider the working characteristics of the AFWS system and the DYC system under different working conditions, and provide a coordinated strategy for additional yaw torque and additional front wheel steering angle for different working conditions, so that the vehicle can maintain vehicle stability and ride comfort at the same time when turning.

[0055] Step 130: The additional yaw torque is sent to the DYC system so that the DYC system can distribute the additional yaw torque according to the preset distribution rules, thereby obtaining the longitudinal braking force of the four wheel hubs of the electric vehicle.

[0056] Specifically, the upper-level controller in the vehicle control unit sends the additional yaw torque, determined based on the driver's control signals and vehicle status information, to the DYC system. The DYC system uses a preset distribution rule to allocate the additional yaw torque to the motor power of each wheel hub motor. This additional yaw torque is generated by controlling the difference in braking force between the left and right wheels to enhance vehicle stability. There can be various preset distribution rules, which are not specifically limited here.

[0057] Step 140: The additional front wheel steering angle is sent to the AFWS system so that the AFWS system can allocate the additional front wheel steering angle based on the preset steering control rules, thereby obtaining the steering angles of the four wheel hubs of the electric vehicle.

[0058] Specifically, the upper-level controller in the vehicle control unit sends the additional front wheel steering angle, determined based on the driver's operating signals and vehicle status information, to the AFWS system. The AFWS system uses preset steering control rules to distribute the additional front wheel steering angle to the output steering angle of the steering motor in each wheel hub. The preset steering control rules typically control the rear wheels to steer along with the front wheels. Therefore, there can be various steering control rules, such as a fixed difference between the rear wheel steering angle and the front wheel steering angle, or a fixed ratio between the rear wheel steering angle and the front wheel steering angle, etc., which are not specifically limited here.

[0059] The direct yaw moment control method for a four-wheel motor driven electric vehicle provided in this application determines the additional yaw moment and additional front wheel steering angle based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and driver-input steering angle using a preset hybrid control rule. Then, the additional yaw moment is distributed to the hub motors of the four wheel hubs through the DYC system to output braking force, and the additional front wheel steering angle is distributed to the steering motors of the four wheel hubs through the AWFS system to output steering angle. This achieves the coordinated operation of the DYC system and the AWFS system on the electric vehicle chassis, avoiding the lack of driving comfort and stability when a single system performs yaw control, and ultimately significantly improving the stability of the vehicle's lateral control.

[0060] Based on the above technical solution, this method determines the additional yaw moment and additional front wheel steering angle using a preset hybrid control rule based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and steering angle. Specifically, this includes:

[0061] If the current yaw rate and the current sideslip angle of the center of gravity meet the first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current sideslip angle of the center of gravity, the current longitudinal speed and the steering angle.

[0062] If the current yaw rate and the current sideslip angle of the center of gravity meet the second preset condition, then the additional yaw torque and the additional front wheel steering angle are determined by a preset hybrid control algorithm based on the current yaw rate, the current sideslip angle of the center of gravity, the current longitudinal speed and the steering angle.

[0063] Specifically, considering the vehicle's lateral stability and the driver's sense of control using the upper-level controller, the technical solution of this application provides two control modes through preset hybrid control rules: 1. Only outputting the additional front wheel steering angle to the AFWS system, i.e., using the AFWS system for independent control; 2. Hybrid output, i.e., outputting the additional front wheel steering angle to the AFWS system and also outputting the additional yaw moment to the DYC system, using hybrid control of the AFWS system and the DYC system.

[0064] The selection of the two control modes mentioned above is made by detecting the current vehicle operating condition.

[0065] For standalone AFWS control, since DYC applies additional yaw torque through differential driving / braking, it may cause noticeably uncomfortable yaw motion for humans when there are sudden changes in the vehicle's longitudinal dynamics; while compared to DYC, the effect of AFWS is almost negligible due to its smaller range of action. Therefore, when the vehicle's current sideslip angle... When the current yaw rate ω is small, DYC is turned off, and only AFWS can work.

[0066] For hybrid AFWS-DYC control, when the vehicle's current sideslip angle and current yaw rate increase, AFWS cannot provide sufficient side tire pressure to maintain vehicle stability. However, DYC plays a central role in stabilizing the vehicle by differential driving / braking in these areas. Therefore, when When ω increases, the hybrid AFWS-DYC control mode will ensure the vehicle's lateral stability and safety.

[0067] Therefore, a hazard coefficient characterizing the vehicle's current operating condition can be constructed using the vehicle's current sideslip angle and current yaw rate. This hazard coefficient is constructed with both the current sideslip angle and the current yaw rate positively correlated. When the hazard coefficient is less than a preset threshold, standalone AFWS control is used; when the hazard coefficient is greater than the preset threshold, hybrid AFWS-DYC control is used. There are various methods for constructing the hazard coefficient, including linear weighting of the current sideslip angle and current yaw rate, higher-order weighting of these parameters, etc., without specific limitations here.

[0068] Based on any of the above technical solutions, in this method, if the current yaw rate and the current sideslip angle meet a first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current sideslip angle, the current longitudinal speed, and the steering angle; if the current yaw rate and the current sideslip angle meet a second preset condition, then the additional yaw torque and the additional front wheel steering angle are determined using a preset hybrid control algorithm based on the current yaw rate, the current sideslip angle, the current longitudinal speed, and the steering angle, specifically including:

[0069] The first cost function of the DYC system and the second cost function of the AFWS system are determined based on the current yaw rate, current centroid sideslip angle, current longitudinal speed and steering angle. The first cost function includes the additional yaw moment to be determined and the corresponding moment weighting coefficient, and the second cost function includes the additional front wheel steering angle to be determined and the corresponding angle weighting coefficient.

[0070] Determine the current hazard factor based on the current yaw rate and the current sideslip angle of the center of gravity;

[0071] If the current risk factor is less than the preset threshold, the torque weighting coefficient and the angle weighting coefficient are set to the first weighting combination;

[0072] If the current risk factor is greater than the preset threshold, the torque weighting coefficient and the angle weighting coefficient are set to the second weighting combination, which is determined based on the current risk factor.

[0073] The coordinated control rule based on the Stackelberg equilibrium strategy constructs an optimization problem for the first cost function and the second cost function. Based on the optimal solution of the optimization problem, the additional front wheel steering angle and additional yaw moment are determined. The additional yaw moment determined by the optimal solution of the corresponding optimization problem constructed using the first weight combination is zero.

[0074] Specifically, to achieve the optimal control objectives of DYC and AFWS, this technology employs a coordinated control strategy based on Stackelberg equilibrium. Stackelberg equilibrium is a collaborative control mode involving a leader and a follower. Since DYC plays a primary role in ensuring vehicle stability, this technology treats DYC as the leader, making decisions first by considering its own constraints and the responses of AFWS (the follower), while the follower simply responds to DYC's decisions.

[0075] In the AFWS-DYC cooperative transverse stability control problem, DYC attempts to address the issue by considering control variables. The number of [something] is used to reduce state errors. Based on this characteristic, the cost function of DYC is constructed. It can be represented as:

[0076]

[0077] in, Let be the state error at time step in the th stage. for Time step at the first The state error at each stage, for Time step at the first Additional yaw moment at each stage, This is the state error weight matrix, whose values ​​are related to the terminal state error weights. same, This is the weight matrix (i.e., torque weight coefficients) of DYC. For time steps, Let be the total number of decision-making stages within a time step, and .

[0078] The cost function for AFWS is constructed in the same way to reduce errors in state variables and additional steering angles. The corresponding cost function... Represented as:

[0079]

[0080] in, for Time step at the first Additional front wheel steering angle at each stage, This is the state error weight matrix, and its values ​​are related to the terminal state error weight matrix. same, This is the weight matrix (i.e., angle weight coefficients) of AFWS. Let be the total number of decision-making stages, and ;

[0081] (i = 1,2) and The standard form of (i = 1, 2) is shown in the following formula:

[0082]

[0083] in, Current centroid sideslip angle The weights, The weights are the current yaw rate ω. Additional front wheel steering angle to be determined The weights, and Additional yaw moment to be determined The weights.

[0084] For the switching between single AFWS control and hybrid AFWS-DYC control modes, the technical solution of this application achieves this by adjusting the weighting coefficient at the input of the upper-level controller, that is, by adjusting the angle weighting coefficient. and torque weighting coefficient This is achieved by... In single AFWS control mode, only the AFWS steering system can guarantee vehicle stability. The weighting coefficients of the AFWS control mode... and Defined as:

[0085]

[0086] Therefore, in the single AFWS mode, by weighting The value is set to infinity to ensure that the DYC output limit is 0. When using the hybrid AFWS-DYC control mode, to reduce the impact of DYC on the driver, this application's technical solution designs an adaptive weight adjustment mechanism. As the lateral force decreases, the control authority of DYC also decreases to ensure that AFWS provides more lateral tire pressure to stabilize the vehicle. When the control authority of DYC decreases, the vehicle body increases additional yaw moment, thereby reducing driver discomfort. Adaptive weight coefficient. and The definition is as follows:

[0087]

[0088] in:

[0089] Where DF represents the current risk level. ω is the current sideslip angle of the center of mass, and ω is the current yaw rate. and All are weighted coefficients.

[0090] It should be noted that when the current risk factor is less than the preset threshold, the torque weight coefficient and angle weight coefficient are set to the first weight combination to ensure that the output limit of the DYC system is 0, thus realizing the control of the AFWS system alone. When the current risk factor is greater than the preset threshold, the torque weight coefficient and angle weight coefficient are set to the second weight combination to realize the hybrid AFWS-DYC control.

[0091] Preferably, the preset threshold can be determined as follows: and They are 20 and 1 respectively, when and The DF value is calculated at that time.

[0092] Then, the first cost function is applied using a coordinated control rule based on the Stackelberg equilibrium strategy. Second cost function Optimize and determine the additional front wheel steering angle. and additional yaw moment In the Stackelberg equilibrium strategy, the coordination control rule sets the DYC system as the leader and the AFWS system as the follower. Therefore, it first minimizes the second cost function. The optimal game response is determined as the additional front wheel steering angle required by the AFWS system, and then minimized by the first cost function. The optimal game response is determined as the initial additional yaw moment. Finally, the additional yaw moment required by the final DYC system is determined based on the additional front wheel steering angle and the initial additional yaw moment.

[0093] Based on any of the above technical solutions, in this method, a first cost function for the DYC system and a second cost function for the AFWS system are determined based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and steering angle. The first cost function includes the additional yaw moment to be determined and the corresponding moment weighting coefficient, and the second cost function includes the additional front wheel steering angle to be determined and the corresponding angle weighting coefficient. Specifically, it includes:

[0094] The state error equation is determined based on the current yaw rate, current centroid sideslip angle, current longitudinal velocity, and steering angle.

[0095] The first cost function of the DYC system is determined based on the state error equation, the additional yaw moment to be determined, and the corresponding moment weighting coefficient.

[0096] The second cost function of the AFWS system is determined based on the state error equation, the undetermined additional front wheel steering angle, and the corresponding angle weighting coefficient.

[0097] Specifically, the state error equation is first determined based on the control guidance model of a two-degree-of-freedom vehicle. The specific process is as follows:

[0098] The purpose of the upper-level controller provided in this application is to ensure that the vehicle stably follows the motion state required by the driver. Assuming that the steering characteristics of the left and right tires are the same, the lateral and yaw motion equations can be expressed by the following formulas.

[0099]

[0100]

[0101] in, and These are the vehicle's current sideslip angle and current yaw rate, respectively. and These are the front and rear wheel steering angles generated by the driver's control; and These are the additional front wheel steering angle and the rear wheel steering angle, respectively. This is the total steering angle of the front wheels. This is the total steering angle of the rear wheels; and These are the lateral tire forces of the front and rear wheels, respectively. It is the additional yaw moment generated by the DYC system. For the total mass of the vehicle. Let be the longitudinal velocity, and a and b be the distances from the vehicle's center of gravity to the front and rear axles, respectively. For inertial torque, and This represents the positive cornering stiffness of the front and rear axles.

[0102] Therefore, the canonical state equation for the linear single-track dynamic model is derived as follows:

[0103] And satisfy,

[0104] in, As a state variable, based on the steering angle input by the driver. The desired yaw rate can be obtained. And the expected centroid side slip angle The response is expressed by the following formula:

[0105]

[0106] in, and Let be a time constant, and:

[0107]

[0108] Therefore, the state error equation can be expressed by the following formula:

[0109]

[0110]

[0111] in, The desired state response of the vehicle can be further represented by the discrete-form state error equation, as shown in the following formula:

[0112]

[0113] in, For sampling time, and To make the error Approaching zero yields the corresponding and .

[0114] Based on the known state error equation, the first cost function of the DYC system is then constructed. It can be done using the following formula:

[0115]

[0116]

[0117] in, for Time step at the first The state error at each stage for Time step at the first The state error at each stage, for Time step at the first Additional yaw moment at each stage, This is the state error weight matrix, whose values ​​are related to the terminal state error weights. same, This is the weight matrix (i.e., torque weight coefficients) of DYC. For time steps, Let be the total number of decision-making stages within a time step, and .

[0118] Correspondingly, construct the second cost function of the AFWS system. It can be done using the following formula:

[0119]

[0120]

[0121] in, for Time step at the first Additional front wheel steering angle at each stage, This is the state error weight matrix, and its values ​​are related to the terminal state error weight matrix. same, This is the weight matrix (i.e., angle weight coefficients) of AFWS. Let be the total number of decision-making stages, and .

[0122] Furthermore, in solving the optimization problems of constructing the first cost function and the second cost function, the optimization problems can be further simplified to the following form:

[0123] ;

[0124]

[0125] in, for Time step at the first Each stage corresponds to the Lagrange operator for determining the additional front wheel steering angle. for State error at time step It is also a constraint;

[0126]

[0127]

[0128] in, for Time step at the first Each stage corresponds to the Lagrange operator for the additional yaw moment to be determined. for State error at time step It is also a constraint.

[0129] Based on any of the above technical solutions, in this method, the first cost function and the second cost function are optimized using a coordinated control rule based on the Stackelberg equilibrium strategy to determine the additional front wheel steering angle and the additional yaw moment, specifically including:

[0130] The optimization objective is to minimize the value of the second cost function, thereby obtaining the corresponding additional front wheel steering angle.

[0131] The optimization objective is to minimize the value of the first cost function, and the corresponding initial additional yaw moment is obtained.

[0132] The additional yaw moment is determined based on the initial additional yaw moment and the additional front wheel steering angle.

[0133] Specifically, the coordination control rule based on the Stackelberg equilibrium strategy first uses the second cost function. The optimization objective is to minimize the value of the additional front wheel steering angle because the leader (DYC) needs to consider the follower's (AFWS) reaction when making decisions. Therefore, the AFWS is determined first. The optimal game response can be constructed as follows:

[0134] ;

[0135] in, for Time step at the first Each stage corresponds to the Lagrange operator for determining the additional front wheel steering angle. for State error at time step It is also a constraint;

[0136] The aforementioned minimum value problem is a standard optimization problem. This technique uses the Lagrange multiplier method to solve this problem and obtains the optimal front wheel steering angle that satisfies coordinated control. .

[0137] Furthermore, the Leader Game-Optimal Control (DYC) problem can be constructed in the following form:

[0138]

[0139] in, for Time step at the first Each stage corresponds to the Lagrange operator for the additional yaw moment to be determined. for State error at time step It is also a constraint.

[0140] To implement the coordinated control strategy in the Stackelberg game, the leader (DYC) first uses the Lagrange multiplier method to solve the optimization problem in the above equation to obtain the optimal output initial additional yaw moment. Then, when making the decision, the actions of the follower (AFWS) were also considered. The yaw moment equivalent to the additional front wheel steering angle executed by the AFWS was removed, and the remaining part is equivalent to the final additional yaw moment that still needs to be executed by the DYC. Calculate the final additional yaw moment. The formula is as follows:

[0141]

[0142] in, For the final determined additional yaw moment, To provide an initial additional yaw moment, The lateral stiffness of the front axle tires. This is the distance from the center of mass to the front axle.

[0143] The above formula provides the equivalent conversion relationship between the additional front wheel steering angle and the yaw moment. First, the additional front wheel steering angle is determined. It is equivalent to providing This value represents the additional yaw moment, so the final additional yaw moment is the initial additional yaw moment obtained from the optimization problem, minus the additional yaw moment provided by the front wheel steering angle.

[0144] Based on any of the above technical solutions, in this method, the preset allocation rule is to take the minimum sum of the tire utilization rates corresponding to the four wheel hubs as the optimization objective, and under preset constraints, determine the braking force of the corresponding four wheel hubs respectively.

[0145] Specifically, the vehicle is equipped with four in-wheel motors and a steering motor via wires as end effectors. Therefore, the virtual control commands obtained from the higher-level controller... and This needs to be further implemented by the actual executor. Among them, The additional yaw torque is sent from the upper controller to the DYC system, which then distributes it to the drive motors of the four wheel hubs to output their respective braking forces.

[0146] The DYC system uses a preset allocation rule that distributes different braking torques to the four wheels. This can be considered a constrained optimization problem. Tire utilization is an important indicator of vehicle stability. Therefore, the optimization problem is defined as minimizing the sum of the utilization rates of the four tires as the optimization objective. The constraints are the dynamic equation, no additional deceleration, the longitudinal force of each tire not exceeding the maximum friction force provided by the road surface, and the friction limit of each tire. This can be expressed by the following formula:

[0147]

[0148] The constraints are:

[0149] in, The longitudinal tire pressure matrix consists of the front left, front right, rear left, and rear right tires. The road adhesion coefficient, The rolling radius of the tire. and These are the vertical force and the lateral force on the tire, respectively. This is to meet the overall longitudinal braking force requirements.

[0150] This small nonlinear optimization problem with multiple constraints is solved using Sequential Quadratic Programming (SQP), and the final result is obtained. The longitudinal tire pressure design scheme for the four tires is as follows: .

[0151] Based on any of the above technical solutions, in this method, the preset steering control rules are to determine that the additional steering angles of the two wheel hubs on the front axle are both additional front wheel steering angles, and to determine that the additional steering angles of the two wheel hubs on the rear axle are both additional front wheel steering angles multiplied by a preset ratio.

[0152] Specifically, the vehicle is equipped with four in-wheel motors and a steering motor via wires as end effectors. Therefore, the virtual control commands obtained from the higher-level controller... and This needs to be further implemented by the actual executor. Among them, The upper-level controller sends the information to the AFWS system, which then distributes the additional front wheel steering angle to the steering motors of the four wheel hubs, outputting their respective steering angles.

[0153] For the AFWS system, it is assumed that the steering angles on the same axis are the same, i.e. , ,in, and These are the steering angles of the left front and right front wheels, respectively. and These are the steering angles of the left and right rear wheels, respectively. The additional rear wheel steering angle can be obtained using the following formula:

[0154]

[0155] in, This is a preset ratio.

[0156] Therefore, additional steering control commands and It can be directly assigned to the steering motor and executed through secondary lead wire technology.

[0157] Based on any of the above technical solutions, this application provides a control method for a lateral stability cooperative controller for electric vehicles based on AFWS and DYC. Figure 2 is a structural diagram of the lateral stability cooperative controller for electric vehicles based on AFWS and DYC provided in this application. As shown in Figure 2, the method includes:

[0158] 1) Establish a control and guidance model for a two-degree-of-freedom vehicle, and obtain the yaw rate based on the input steering angle. and centroid side slip angle The expected value is determined, and the state error equation of the vehicle is determined.

[0159] The purpose of the upper-level controller provided in this application is to ensure that the vehicle stably follows the motion state required by the driver. Assuming that the steering characteristics of the left and right tires are the same, the lateral and yaw motion equations can be expressed by the following formulas.

[0160]

[0161]

[0162] in, and These are the vehicle's current sideslip angle and current yaw rate, respectively. and These are the front and rear wheel steering angles generated by the driver's control; and These are the additional front wheel steering angle and the rear wheel steering angle, respectively. This is the total steering angle of the front wheels. This is the total steering angle of the rear wheels; and These are the lateral tire forces of the front and rear wheels, respectively. It is the additional yaw moment generated by the DYC system. For the total mass of the vehicle. Let be the longitudinal velocity, and a and b be the distances from the vehicle's center of gravity to the front and rear axles, respectively. For inertial torque, and This represents the positive cornering stiffness of the front and rear axles.

[0163] Therefore, the canonical state equation for the linear single-track dynamic model is derived as follows:

[0164]

[0165] And satisfy,

[0166] in, As a state variable, based on the steering angle input by the driver. The desired yaw rate can be obtained. And the expected centroid side slip angle The response is expressed by the following formula:

[0167]

[0168] in, and Let be a time constant, and:

[0169]

[0170] Therefore, the state error equation can be expressed by the following formula:

[0171]

[0172]

[0173] in, The desired state response of the vehicle can be further represented by the discrete-form state error equation, as shown in the following formula:

[0174]

[0175] in, For sampling time, and To make the error Approaching zero yields the corresponding and .

[0176] 2) Design the upper-level controller according to different control modes, including the modeling and design of direct yaw torque control (DYC) and active four-wheel steering system (AFWS).

[0177] Considering the lateral stability of the vehicle and the driver's sense of control using the upper controller, this technology defines two control modes: (1) single AFWS control and (2) hybrid AFWS-DYC control.

[0178] 2.1 Single AFWS Control

[0179] Because DYC applies additional yaw torque through differential driving / braking, sudden changes in vehicle longitudinal dynamics can cause noticeably uncomfortable yaw motions for humans. In contrast, the effect of AFWS is almost negligible due to its smaller range of action. Therefore, when the sideslip angle and yaw rate are small, DYC is deactivated, and only AFWS can operate.

[0180] 2.2 Hybrid AFWS-DYC Control

[0181] When the centroid side slip angle and yaw rate When the pressure increases, the AFWS cannot provide sufficient side tire pressure to maintain vehicle stability, but DYC can play a central role in stabilizing the vehicle through differential driving / braking in these areas. Therefore, when and When the load increases, the hybrid AFWS-DYC control mode will ensure the vehicle's lateral stability and safety.

[0182] In addition, sideslip angle and yaw rate These are two important parameters representing the lateral stability of a vehicle. This technology uses a coefficient-weighted method to construct hazard factors (DF) to represent the vehicle's hazard level, as shown below:

[0183] (11)

[0184] in, and For the weights, and , First, calculate the critical value of DF. The method for determining is when and The DF value is determined at that time. Specifically, the technical solution of this application is divided into two cases: when When AFWS provides stable vehicle control, it is chosen to ensure vehicle stability; however, when A single AFWS control cannot provide sufficient tire pressure measurement to ensure vehicle stability. Therefore, an AFWS-DYC hybrid control is adopted to ensure safe vehicle operation.

[0185] 3) Establish a coordinated control strategy for DYC and AFWS based on Stackelberg game theory, and construct a cost function and optimization method to obtain virtual control commands from the upper-level controller. and .

[0186] To achieve the optimal control objectives of DYC and AFWS, this technology employs a coordinated control strategy based on Stackelberg equilibrium. Stackelberg equilibrium is a cooperative control mode involving a leader and a follower. Since DYC plays a primary role in ensuring vehicle stability, this technology treats DYC as the leader, making decisions first by considering its own constraints and the responses of AFWS (the follower), while the follower simply responds to DYC's decisions.

[0187] In the AFWS-DYC cooperative transverse stability control problem, DYC attempts to address the issue by considering control variables. The number of [something] is used to reduce state errors. Based on this characteristic, the cost function of DYC is constructed. It can be represented as:

[0188]

[0189] in, for Time step at the first The state error at each stage for Time step at the first The state error at each stage, for Time step at the first Additional yaw moment at each stage, This is the state error weight matrix, whose values ​​are related to the terminal state error weights. same, This is the weight matrix (i.e., torque weight coefficients) of DYC. For time steps, Let be the total number of decision-making stages within a time step, and .

[0190] The cost function for AFWS is constructed in the same way to reduce errors in state variables and additional steering angles. The corresponding cost function... Represented as:

[0191]

[0192] in, for Time step at the first Additional front wheel steering angle at each stage, This is the state error weight matrix, and its values ​​are related to the terminal state error weight matrix. same, This is the weight matrix (i.e., angle weight coefficients) of AFWS. Let be the total number of decision-making stages, and ;

[0193] and The standard form of is shown in the following formula:

[0194]

[0195] in, Current centroid sideslip angle The weights, Current yaw rate The weights, Additional front wheel steering angle to be determined The weights, and Additional yaw moment to be determined The weights.

[0196] For the switching between single AFWS control and hybrid AFWS-DYC control modes, the technical solution of this application achieves this by adjusting the weighting coefficient at the input of the upper-level controller, that is, by adjusting the angle weighting coefficient. and torque weighting coefficient This is achieved by... In single AFWS control mode, only the AFWS steering system can guarantee vehicle stability. The weighting coefficients of the AFWS control mode... and Defined as:

[0197]

[0198] Therefore, in the single AFWS mode, by weighting The value is set to infinity to ensure that the DYC output limit is 0. When using the hybrid AFWS-DYC control mode, to reduce the impact of DYC on the driver, this application's technical solution designs an adaptive weight adjustment mechanism. As the lateral force decreases, the control authority of DYC also decreases to ensure that AFWS provides more lateral tire pressure to stabilize the vehicle. When the control authority of DYC decreases, the vehicle body increases additional yaw moment, thereby reducing driver discomfort. Adaptive weight coefficient. and The definition is as follows:

[0199]

[0200] in:

[0201] Where DF represents the current risk level. The weights are the current centroid sideslip angles. The current yaw rate, and All are weighted coefficients.

[0202] In designing optimization methods for coordination and control strategies, since leaders need to consider the reactions of their followers (AFWS) when making decisions, the AFWS must first be determined. The optimal game response can be constructed as follows:

[0203]

[0204] in, for Time step at the first Each stage corresponds to the Lagrange operator for the undetermined additional front wheel steering angle, with the following constraints:

[0205]

[0206] This problem is a standard optimization problem. This technique uses the Lagrange multiplier method to solve the problem and obtain the optimal front wheel steering angle that satisfies coordinated control. .

[0207] Furthermore, the Leader Game-Optimal Control (DYC) problem can be constructed in the following form:

[0208]

[0209] in, for Time step at the first Each stage corresponds to the Lagrange operator for the undetermined additional yaw moment, with the following constraints:

[0210] .

[0211] To implement the coordinated control strategy in the Stackelberg game, the leader (DYC) first uses the Lagrange multiplier method to solve the optimization problem in the above equation to obtain the optimal output initial additional yaw moment. Then, when making the decision, the actions of the follower (AFWS) were also considered. The yaw moment equivalent to the additional front wheel steering angle executed by the AFWS was removed, and the remaining part is equivalent to the final additional yaw moment that still needs to be executed by the DYC. Calculate the final additional yaw moment. The formula is as follows:

[0212]

[0213] in, For the final determined additional yaw moment, To provide an initial additional yaw moment, The lateral stiffness of the front axle tires. This is the distance from the center of mass to the front axle.

[0214] The above formula provides the equivalent conversion relationship between the additional front wheel steering angle and the yaw moment. First, the additional front wheel steering angle is determined. It is equivalent to providing This value represents the additional yaw moment, so the final additional yaw moment is the initial additional yaw moment obtained from the optimization problem, minus the additional yaw moment provided by the front wheel steering angle.

[0215] 4) Design a lower-level controller to enable the virtual control commands obtained from the upper-level controller. and This is applied to real executors to achieve task allocation among underlying distributed executors.

[0216] The target vehicle is equipped with four in-wheel motors and a steering motor via wires as the end effector. Therefore, the virtual control commands obtained from the higher-level controller... and This needs to be further implemented by an actual actuator. Drive / Brake Torque and steering angle It should be determined in the lower-level controller. These represent the front left, front right, rear left, and rear right tires, respectively. Assume that the steering angles on the same axle are the same. , .

[0217] For AFWS, the additional rear wheel steering angle is obtained according to the following formula:

[0218]

[0219] Therefore, additional steering control commands and It can be directly assigned to the steering motor and executed through secondary lead wire technology.

[0220] For DYC, by distributing different drive / braking torques to the four wheels, this can be considered a constrained optimization problem. Tire utilization is an important indicator of vehicle stability. Therefore, the optimization problem is defined as minimizing the sum of the utilization rates of the four tires as the optimization objective. The constraints are the dynamic equation, no additional deceleration, the longitudinal force of each tire not exceeding the maximum friction force provided by the road surface, and the friction limit of each tire. This can be expressed by the following formula:

[0221]

[0222] The constraints are:

[0223] in, The longitudinal tire pressure matrix consists of the front left, front right, rear left, and rear right tires. The road adhesion coefficient, The rolling radius of the tire. and tires Vertical and lateral forces, This is to meet the overall longitudinal braking force requirements.

[0224] This small nonlinear optimization problem with multiple constraints is solved using Sequential Quadratic Programming (SQP), and the final result is obtained. The longitudinal tire pressure design scheme for the four tires is as follows: .

[0225] 5) Detect the steering angle input by the driver at the current moment, measure the corresponding actuator information, and use the upper-level controller to obtain the additional yaw torque that DYC and AFWS need to compensate for respectively. and additional steering angle of the front wheels The system then uses a lower-level controller to convert the two control variables into output signals for the actual actuators, thereby improving the stability of the vehicle's lateral control.

[0226] The following describes the device technical solution of this application, which can be used to execute the electric vehicle lateral stability cooperative control method in the above-described technical solution of this application. For details not disclosed in the device technical solution of this application, please refer to the technical solution of the electric vehicle lateral stability cooperative control method described above in this application.

[0227] Based on any of the above technical solutions, Figure 3 is a structural schematic diagram of the electric vehicle lateral stability cooperative control device provided in this application. As shown in Figure 3, the device includes an acquisition unit 310, a determination unit 320, a first sending unit 330, and a second sending unit 340, wherein...

[0228] The acquisition unit 310 is used to acquire the current yaw rate, current center of gravity sideslip angle and current longitudinal speed of the electric vehicle, as well as the steering angle input by the driver;

[0229] The determining unit 320 is used to determine the additional yaw moment and the additional front wheel steering angle based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle using a preset hybrid control rule;

[0230] The first transmitting unit 330 is used to transmit the additional yaw torque to the DYC system so that the DYC system can distribute the additional yaw torque according to the preset distribution rules, thereby obtaining the longitudinal braking force of the four wheel hubs of the electric vehicle respectively.

[0231] The second sending unit 340 is used to send the additional front wheel steering angle to the AFWS system so that the AFWS system can allocate the additional front wheel steering angle based on the preset steering control rules, thereby obtaining the steering angles of the four wheel hubs of the electric vehicle respectively.

[0232] The device provided in this application determines the additional yaw torque and additional front wheel steering angle based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and driver-input steering angle using a preset hybrid control rule. Then, the additional yaw torque is distributed to the wheel hub motors of the four wheel hubs through the DYC system to output braking force, and the additional front wheel steering angle is distributed to the steering motors of the four wheel hubs through the AWFS system to output steering angle. This realizes the coordinated work of the DYC system and the AFWS system on the electric vehicle chassis, avoiding the lack of driving comfort and stability when a single system performs yaw control, and ultimately significantly improving the stability of vehicle lateral control.

[0233] Based on any of the above technical solutions, in this device, the determining unit is specifically used for:

[0234] If the current yaw rate and the current sideslip angle of the center of gravity meet the first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current sideslip angle of the center of gravity, the current longitudinal speed and the steering angle.

[0235] If the current yaw rate and the current sideslip angle of the center of gravity meet the second preset condition, then the additional yaw torque and the additional front wheel steering angle are determined by a preset hybrid control algorithm based on the current yaw rate, the current sideslip angle of the center of gravity, the current longitudinal speed and the steering angle.

[0236] Based on any of the above technical solutions, in this device, the determining unit is specifically used for:

[0237] The first cost function of the DYC system and the second cost function of the AFWS system are determined based on the current yaw rate, current centroid sideslip angle, current longitudinal speed and steering angle. The first cost function includes the additional yaw moment to be determined and the corresponding moment weighting coefficient, and the second cost function includes the additional front wheel steering angle to be determined and the corresponding angle weighting coefficient.

[0238] Determine the current hazard factor based on the current yaw rate and the current sideslip angle of the center of gravity;

[0239] If the current risk factor is less than the preset threshold, the torque weighting coefficient and the angle weighting coefficient are set to the first weighting combination;

[0240] If the current risk factor is greater than the preset threshold, the torque weighting coefficient and the angle weighting coefficient are set to the second weighting combination, which is determined based on the current risk factor.

[0241] The first and second cost functions are optimized using a coordinated control rule based on the Stackelberg equilibrium strategy to determine the additional front wheel steering angle and additional yaw moment.

[0242] Based on any of the above technical solutions, in this device, the first cost function and the second cost function are optimized using a coordinated control rule based on the Stackelberg equilibrium strategy to determine the additional front wheel steering angle and the additional yaw moment, specifically including:

[0243] The optimization objective is to minimize the value of the second cost function, thereby obtaining the corresponding additional front wheel steering angle.

[0244] The optimization objective is to minimize the value of the first cost function, and the corresponding initial additional yaw moment is obtained.

[0245] The additional yaw moment is determined based on the initial additional yaw moment and the additional front wheel steering angle.

[0246] Based on any of the above technical solutions, in this device, a first cost function for the DYC system and a second cost function for the AFWS system are determined based on the current yaw rate, current center of gravity sideslip angle, current longitudinal velocity, and steering angle. The first cost function includes the additional yaw moment to be determined and the corresponding moment weighting coefficient, and the second cost function includes the additional front wheel steering angle to be determined and the corresponding angle weighting coefficient. Specifically, it includes:

[0247] The state error equation is determined based on the current yaw rate, current centroid sideslip angle, current longitudinal velocity, and steering angle.

[0248] The first cost function of the DYC system is determined based on the state error equation, the additional yaw moment to be determined, and the corresponding moment weighting coefficient.

[0249] The second cost function of the AFWS system is determined based on the state error equation, the undetermined additional front wheel steering angle, and the corresponding angle weighting coefficient.

[0250] Based on any of the above technical solutions, in this device, the preset allocation rule is to minimize the sum of the tire utilization rates corresponding to the four wheel hubs, and under preset constraints, determine the braking force of the corresponding four wheel hubs.

[0251] Based on any of the above technical solutions, in this device, the preset steering control rules are to determine that the additional steering angles of the two wheel hubs on the front axle are both additional front wheel steering angles, and to determine that the additional steering angles of the two wheel hubs on the rear axle are both additional front wheel steering angles multiplied by a preset ratio.

[0252] Figure 4 illustrates a schematic diagram of the physical structure of an electric vehicle. As shown in Figure 4, the electric vehicle may include: a processor 410, a communication interface 420, a memory 430, and a communication bus 440. The processor 410, the communication interface 420, and the memory 430 communicate with each other through the communication bus 440. The processor 410 can call logic instructions in the memory 430 to execute a lateral stability cooperative control method for electric vehicles. The method includes: acquiring the current yaw rate, current center of gravity sideslip angle, and current longitudinal speed of the electric vehicle, as well as the steering angle input by the driver; determining an additional yaw torque and an additional front wheel steering angle based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and steering angle using a preset hybrid control rule; sending the additional yaw torque to the DYC system so that the DYC system can allocate the additional yaw torque according to a preset allocation rule to obtain the longitudinal braking force of each of the four wheel hubs of the electric vehicle; and sending the additional front wheel steering angle to the AFWS system so that the AFWS system can allocate the additional front wheel steering angle according to a preset steering control rule to obtain the steering angle of each of the four wheel hubs of the electric vehicle.

[0253] Furthermore, the logical instructions in the aforementioned memory 430 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various technical solutions of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0254] On the other hand, this application also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the electric vehicle lateral stability cooperative control method provided by the above methods. The method includes: acquiring the current yaw rate, current center of gravity sideslip angle, and current longitudinal speed of the electric vehicle, as well as the steering angle input by the driver; determining an additional yaw torque and an additional front wheel steering angle based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and steering angle using a preset hybrid control rule; sending the additional yaw torque to the DYC system so that the DYC system can allocate the additional yaw torque according to a preset allocation rule to obtain the longitudinal braking force of each of the four wheel hubs of the electric vehicle; and sending the additional front wheel steering angle to the AFWS system so that the AFWS system can allocate the additional front wheel steering angle according to a preset steering control rule to obtain the steering angle of each of the four wheel hubs of the electric vehicle.

[0255] In another aspect, this application also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements the electric vehicle lateral stability cooperative control method provided by the above methods. The method includes: acquiring the current yaw rate, current center of gravity sideslip angle, and current longitudinal speed of the electric vehicle, as well as the steering angle input by the driver; determining an additional yaw torque and an additional front wheel steering angle based on the current yaw rate, current center of gravity sideslip angle, current longitudinal speed, and steering angle using a preset hybrid control rule; sending the additional yaw torque to the DYC system so that the DYC system can allocate the additional yaw torque according to a preset allocation rule to obtain the longitudinal braking force of each of the four wheel hubs of the electric vehicle; and sending the additional front wheel steering angle to the AFWS system so that the AFWS system can allocate the additional front wheel steering angle according to a preset steering control rule to obtain the steering angle of each of the four wheel hubs of the electric vehicle.

[0256] The device technical solution described above is merely illustrative. The units described as separate components may or may not be physically separate, and 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 modules can be selected to achieve the purpose of this technical solution according to actual needs. Those skilled in the art can understand and implement this solution without any inventive effort.

[0257] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the prior art, can be embodied in the form of software products. These computer software products can be stored in computer-readable storage media, such as ROM / RAM, magnetic disks, optical disks, etc., and include several instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to execute various technical solutions or parts thereof.

[0258] Finally, it should be noted that the above technical solutions are only used to illustrate the technical solutions of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing technical solutions, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing technical solutions, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of this application.

Claims

1. A method for coordinated lateral stability control of an electric vehicle, applied to a vehicle control unit, the method comprising: The current yaw rate, current sideslip angle, and current longitudinal speed of the electric vehicle are obtained, along with the steering angle input by the driver. The additional yaw moment and additional front wheel steering angle are determined based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle using a preset hybrid control rule; The additional yaw moment is sent to the DYC system, so that the DYC system can allocate the additional yaw moment according to the preset allocation rules, thereby obtaining the longitudinal braking force of the four wheel hubs of the electric vehicle respectively. The additional front wheel steering angle is sent to the AFWS system, which then allocates the additional front wheel steering angle based on preset steering control rules, thereby obtaining the steering angles of the four wheel hubs of the electric vehicle.

2. The electric vehicle lateral stability cooperative control method according to claim 1, wherein, The determination of additional yaw moment and additional front wheel steering angle based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed, and the steering angle using a preset hybrid control rule specifically includes: If the current yaw rate and the current center of gravity sideslip angle meet the first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle; If the current yaw rate and the current center of gravity sideslip angle meet the second preset condition, then based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle, a preset hybrid control algorithm is used to determine the additional yaw torque and the additional front wheel steering angle.

3. The electric vehicle lateral stability cooperative control method according to claim 2, wherein, If the current yaw rate and the current center of gravity sideslip angle meet the first preset condition, then the additional yaw torque is determined to be zero, and the additional front wheel steering angle is determined based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle; If the current yaw rate and the current sideslip angle satisfy the second preset condition, then based on the current yaw rate, the current sideslip angle, the current longitudinal velocity, and the steering angle, a preset hybrid control algorithm is used to determine the additional yaw moment and the additional front wheel steering angle, specifically including: Based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed, and the steering angle, a first cost function for the DYC system and a second cost function for the AFWS system are determined. The first cost function includes an additional yaw moment to be determined and a corresponding moment weighting coefficient, and the second cost function includes an additional front wheel steering angle to be determined and a corresponding angle weighting coefficient. The current risk factor is determined based on the current yaw rate and the current centroid sideslip angle. If the current risk factor is less than a preset threshold, then the torque weighting coefficient and the angle weighting coefficient are set to a first weighting combination; If the current risk factor is greater than the preset threshold, then the torque weighting coefficient and the angle weighting coefficient are set as a second weighting combination, wherein the second weighting combination is determined based on the current risk factor; The coordinated control rule based on the Stackelberg equilibrium strategy constructs an optimization problem for the first cost function and the second cost function. Based on the optimal solution of the optimization problem, the additional front wheel steering angle and additional yaw moment are determined. The additional yaw moment determined by the optimal solution of the corresponding optimization problem constructed using the first weight combination is zero.

4. The electric vehicle lateral stability cooperative control method according to claim 3, wherein, The first cost function of the DYC system and the second cost function of the AFWS system are determined based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal velocity, and the steering angle. The first cost function includes an additional yaw moment to be determined and a corresponding moment weighting coefficient, and the second cost function includes an additional front wheel steering angle to be determined and a corresponding angle weighting coefficient. Specifically, this includes: The state error equation is determined based on the current yaw rate, the current centroid sideslip angle, the current longitudinal velocity, and the steering angle. The first cost function of the DYC system is determined based on the state error equation, the additional yaw moment to be determined, and the corresponding moment weighting coefficient. The second cost function of the AFWS system is determined based on the state error equation, the additional front wheel steering angle to be determined, and the corresponding angle weighting coefficient.

5. The electric vehicle lateral stability cooperative control method according to claim 3, wherein, The optimization of the first and second cost functions using a coordinated control rule based on the Stackelberg equilibrium strategy to determine the additional front wheel steering angle and additional yaw moment specifically includes: The optimization objective is to minimize the value of the second cost function, and the corresponding additional front wheel steering angle is obtained. The optimization objective is to minimize the value of the first cost function to obtain the corresponding initial additional yaw moment. The additional yaw moment is determined based on the initial additional yaw moment and the additional front wheel steering angle.

6. The method for coordinated control of lateral stability of electric vehicles according to any one of claims 1-5, wherein, The preset allocation rule is to minimize the sum of the tire utilization rates corresponding to the four wheel hubs as the optimization objective, and to determine the braking force of the four wheel hubs respectively under preset constraints.

7. The method for coordinated control of lateral stability of electric vehicles according to any one of claims 1-5, wherein, The preset steering control rule is to determine that the additional steering angle of each of the two hubs on the front axle is the additional front wheel steering angle, and to determine that the additional steering angle of each of the two hubs on the rear axle is the additional front wheel steering angle multiplied by a preset ratio.

8. A lateral stability cooperative control device for electric vehicles, the device comprising: The acquisition unit is used to acquire the current yaw rate, current sideslip angle, and current longitudinal speed of the electric vehicle, as well as the steering angle input by the driver. The determining unit is used to determine the additional yaw moment and the additional front wheel steering angle based on the current yaw rate, the current center of gravity sideslip angle, the current longitudinal speed and the steering angle using a preset hybrid control rule; The first transmitting unit is used to transmit the additional yaw moment to the DYC system, so that the DYC system can allocate the additional yaw moment according to the preset allocation rules to obtain the longitudinal braking force of the four wheel hubs of the electric vehicle respectively. The second transmitting unit is used to transmit the additional front wheel steering angle to the AFWS system, so that the AFWS system can allocate the additional front wheel steering angle based on the preset steering control rules, thereby obtaining the steering angles of the four wheel hubs of the electric vehicle respectively.

9. A computer-readable storage medium storing at least one piece of program code, the at least one piece of program code being loaded and executed by a processor to perform the operations performed by the electric vehicle lateral stability cooperative control method as described in any one of claims 1 to 7.

10. An electric vehicle comprising one or more processors and one or more memories, wherein at least one piece of program code is stored in the one or more memories, the at least one piece of program code being loaded and executed by the one or more processors to perform the operations performed by the electric vehicle lateral stability cooperative control method as claimed in any one of claims 1 to 7.

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