Vehicle torque distribution control method and device, storage medium and program product

Abstract

The invention discloses a vehicle torque distribution control method and device, a storage medium and a program product, and relates to the technical field of vehicle control. The method comprises the steps that motion state data of a vehicle and a steering request input by a driver are obtained; a reference quantity is established through the two-degree-of-freedom vehicle dynamics model; the reference quantity and the motion state data are input into an upper-layer controller, additional yaw moment is obtained, and the upper-layer controller is a yaw controller designed through a backstepping type nonlinear control method; and the additional yawing moment and the motion state data are input into a lower-layer controller, the additional motor torque of the vehicle is obtained, and the lower-layer controller is a torque controller designed through a wheel dynamics model. Due to the fact that backstepping and optimization of the upper-layer controller and the lower-layer controller are combined, the longitudinal stability and the transverse stability of the vehicle can be ensured, the stability of the four-wheel independent drive vehicle under extreme conditions is improved, and interference to expectation of a driver is reduced.

Description

Technical Field

[0001] The present application relates to the field of vehicle control technology, and in particular to a vehicle torque distribution control method, device, storage medium and program product. Background Art

[0002] With the rapid development of the automobile industry and the continuous improvement of road traffic safety requirements, vehicle stability control has become one of the core technologies in the field of active automobile safety. Vehicles may face various complex road conditions and emergencies during driving, such as sharp turns, emergency avoidance, slippery roads, etc., all of which may cause vehicle instability. Vehicle stability control can assist the driver to maintain vehicle stability and reduce the occurrence of traffic accidents through advanced sensing, control and execution technologies when dangerous situations occur.

[0003] Traditional stability control is generally implemented through sliding mode control (SMC), which is a nonlinear control method. The core idea of ​​SMC is to design a sliding surface and force the system state to move along the sliding surface. In vehicle stability control, SMC can effectively handle system parameter uncertainty and external interference, and achieve fast and accurate yaw rate tracking control. However, this method may interfere with the driver's torque demand. Unlike traditional internal combustion engine vehicles with differential braking systems, four-wheel drive vehicles can generate positive and negative torques to adjust vehicle motion. The introduction of positive torque may unexpectedly cause acceleration, causing panic and discomfort. Summary of the invention

[0004] The main purpose of the present application is to provide a vehicle torque distribution control method, device, storage medium and program product, aiming to solve the technical problem that the traditional stability control method interferes with the driver's torque demand.

[0005] To achieve the above objectives, the present application proposes a vehicle torque distribution control method, the method comprising:

[0006] Acquire the vehicle's motion state data and the steering request input by the driver;

[0007] Establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request;

[0008] Inputting the reference amount and the motion state data into an upper controller to obtain an additional yaw moment, wherein the upper controller is a yaw controller designed by a backstepping nonlinear control method;

[0009] The additional yaw moment and the motion state data are input into a lower-level controller to obtain an additional motor torque of the vehicle. The lower-level controller is a torque controller designed by a wheel dynamics model.

[0010] In one embodiment, the step of establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request comprises:

[0011] determining an angle at which a driver controls a steering wheel according to the steering request;

[0012] constructing a reference yaw rate based on the angle of the steering wheel;

[0013] A reference quantity is generated by a two-degree-of-freedom vehicle dynamics model according to the motion state data and the reference yaw angular velocity.

[0014] In one embodiment, before the step of obtaining the vehicle's motion state data and the steering request input by the driver, the design of the upper controller includes:

[0015] Determine the system tracking error of the upper controller;

[0016] The tracking error of the system is designed according to the Lyapunov function to obtain the upper control law;

[0017] An upper-level controller is designed according to the upper-level control law and the backstepping nonlinear control method.

[0018] In one embodiment, before the step of obtaining the vehicle's motion state data and the steering request input by the driver, the design of the lower-level controller includes:

[0019] Determine the rate of change of the wheel speed tracking error of the vehicle according to the wheel dynamics model;

[0020] The rate of change of the wheel speed tracking error is designed according to the Lyapunov function to obtain the lower control law;

[0021] The lower-level controller is designed according to the preset objective function, the preset constraint conditions and the lower-level control law.

[0022] In one embodiment, the preset objective function includes a first objective function J1, a second objective function J2, a third objective function J3 and a fourth objective function J4;

[0023] The fourth objective function is:

[0024] J = J1 + w2J2 + w3J3;

[0025] Among them, w2 and w3 are optimization weights.

[0026] In one embodiment, the preset constraint condition includes a first constraint condition and a second constraint condition;

[0027] The first constraint condition is:

[0028] 0 <k ij,min ≤k ij ≤k ij,max ;

[0029] Among them, k ij is the slip rate of each tire, k ij,min is the minimum value of slip rate, k ij,max is the maximum value of slip rate;

[0030] The second constraint is:

[0031] |ΔT ij |≤ΔT max ;

[0032] Where |ΔT ij | is the absolute value of the additional motor torque, ΔT max is the maximum additional motor torque.

[0033] In addition, to achieve the above-mentioned purpose, the present application also proposes a vehicle torque distribution control device, the device comprising:

[0034] A data acquisition module, used to acquire the vehicle's motion state data and the steering request input by the driver;

[0035] A reference quantity establishment module, used for establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request;

[0036] A yaw moment module, used for inputting the reference amount and the motion state data into an upper controller to obtain an additional yaw moment, wherein the upper controller is a yaw controller designed by a backstepping nonlinear control method;

[0037] The torque generation module is used to control the additional yaw moment and the motion state data to be input into a lower-level controller to obtain additional motor torque of the vehicle. The lower-level controller is a torque controller designed by a wheel dynamics model.

[0038] In addition, to achieve the above objectives, the present application also proposes a vehicle, which executes the steps of implementing the vehicle torque distribution control method as described above.

[0039] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by the processor, the steps of the vehicle torque distribution control method described above are implemented.

[0040] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the vehicle torque distribution control method described above are implemented.

[0041] One or more technical solutions proposed in this application have at least the following technical effects: this application first obtains the vehicle's motion state data and the steering request input by the driver; then, according to the motion state data and the steering request, a reference quantity is established through a two-degree-of-freedom vehicle dynamics model; then, the reference quantity and the motion state data are input into an upper controller to obtain an additional yaw moment, and the upper controller is a yaw controller designed by a backstepping nonlinear control method; finally, the additional yaw moment and the motion state data are input into a lower controller to obtain an additional motor torque of the vehicle, and the lower controller is a torque controller designed by a wheel dynamics model. Since this application combines backstepping and optimization of the upper and lower controllers, the longitudinal and lateral stability of the vehicle can be ensured, the stability of the four-wheel independent drive vehicle under extreme conditions is improved, and the interference with the driver's expectations is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0044] Figure 1 A schematic diagram of a flow chart provided for the first embodiment of the vehicle torque distribution control method of the present application;

[0045] Figure 2 A schematic diagram of a two-degree-of-freedom vehicle dynamics model provided in Example 1 of the present application;

[0046] Figure 3 A schematic diagram of a wheel dynamics model provided in Example 1 of the present application;

[0047] Figure 4 A control block diagram provided for Embodiment 1 of the present application;

[0048] Figure 5 A schematic diagram of a flow chart provided for the second embodiment of the vehicle torque distribution control method of the present application;

[0049] Figure 6This is a schematic diagram of the module structure of the vehicle torque distribution control device according to an embodiment of the present application;

[0050] Figure 7 Schematic diagram of the device structure of the hardware operating environment involved in the vehicle torque distribution control method in the embodiment of the present application.

[0051] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0053] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0054] It should be noted that the execution subject of this embodiment can be an electronic device with data acquisition, reference establishment and torque distribution functions, such as a vehicle-mounted computer, or an electronic device capable of realizing the above functions, a vehicle torque distribution control device (hereinafter referred to as a control device) that executes the vehicle torque distribution control method of the present application, etc., and this embodiment does not limit this. The following takes the control device as an example to illustrate this embodiment and the following embodiments.

[0055] Based on this, the embodiment of the present application provides a vehicle torque distribution control method, referring to Figure 1 , Figure 1 A flow chart of the first embodiment of the vehicle torque distribution control method of the present application.

[0056] In this embodiment, the vehicle torque distribution control method includes steps S10 to S40:

[0057] Step S10: Acquire the vehicle's motion state data and the steering request input by the driver.

[0058] It should be noted that the motion state data reflects the actual operation of the vehicle on the current road, such as vehicle longitudinal speed, vehicle lateral speed, longitudinal acceleration, lateral acceleration, heading angle, pitch angle, roll angle, etc.

[0059] It should be noted that the steering request is a steering instruction issued by the driver to the vehicle by operating the steering wheel, and specifically may include.

[0060] In this embodiment, the control device can first obtain the vehicle's motion state data, including the vehicle's longitudinal speed, vehicle lateral speed, longitudinal acceleration, lateral acceleration, heading angle, pitch angle, roll angle, etc., as well as the steering request input by the driver, such as front wheel steering angle and other data.

[0061] Step S20: establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request.

[0062] It should be noted that the two-degree-of-freedom (2-DOF) vehicle dynamics model is a simplified model used to describe the dynamic characteristics of a vehicle. In this model, there are usually two main degrees of freedom, such as the lateral motion of the vehicle (such as lateral displacement, sideslip angle, sideslip angle, etc.) and yaw motion (such as yaw rate, etc.).

[0063] Since some relationships in the two-degree-of-freedom vehicle dynamics model are not simple linear relationships, and there may be more complex functional relationships to describe vehicle characteristics, the mechanical properties of the tires can also be used to describe vehicle characteristics in the subsequent model analysis process.

[0064] Specifically, before establishing a reference, it is necessary to establish relevant vehicle models, including a two-degree-of-freedom vehicle dynamics model, a wheel dynamics model, and a tire model. The two-degree-of-freedom vehicle dynamics model considers two degrees of freedom: lateral motion and yaw motion, the wheel dynamics model adjusts the stability of the vehicle's longitudinal slip rate, and the tire model determines the tire force, thereby describing the vehicle characteristics.

[0065] There are two main indicators related to vehicle stability control. First, excessive tire slip must be minimized to ensure stable tire grip. Second, the best response to yaw motion (vehicle rotation around the Z axis) must be made according to the driver's intention to improve the handling performance of the vehicle. In order to consider these two factors at the same time, a two-degree-of-freedom vehicle dynamics model can be used for analysis. This model takes into account the vehicle's yaw rate and sideslip angle, such as Figure 2 As shown, Figure 2 Schematic diagram of a two-degree-of-freedom vehicle dynamics model provided in Example 1 of the present application. The model assumes that the vehicle speed does not change suddenly and has two degrees of freedom: lateral motion and yaw motion. The symbol subscripts FL, FR, RL and RR used in the model represent the left front wheel, the right front wheel, the left rear wheel and the right rear wheel, respectively.

[0066] 1. The construction of the two-degree-of-freedom vehicle dynamics model is as follows:

[0067] The two-degree-of-freedom vehicle dynamics model is as follows Figure 1 , the sideslip angle change rate and yaw rate change rate can be expressed as:

[0068]

[0069] Among them, β is the sideslip angle of the vehicle body, in rad; is the rate of change of the sideslip angle; γ is the yaw rate of the vehicle body, in rad / s; is the rate of change of the yaw rate; F yis the tire lateral force, in N; m is the vehicle mass, in kg; V x is the longitudinal speed of the vehicle, in m / s; M is the yaw torque; ΔM is the additional yaw torque, in Nm; I z is the vehicle's Z-axis moment of inertia, in kg·m2.

[0070] in,

[0071]

[0072] in, is the tire longitudinal force of the left front wheel; is the longitudinal force of the tire on the right front wheel; F is the front wheel steering angle given by the driver, in rad; is the tire lateral force of the left front wheel; is the tire lateral force of the right front wheel; is the tire lateral force of the left rear wheel; is the tire lateral force of the right rear wheel;

[0073] Among them, l F is the distance from the vehicle's center of mass to the front axle, in meters; l R is the distance from the vehicle's center of mass to the rear axle, in meters; w R and w L is the distance from the left and right wheels to the vehicle axis, in meters; is the tire longitudinal force of the left rear wheel; is the longitudinal force of the tire on the right rear wheel.

[0074] 2. The wheel dynamics model is constructed as follows:

[0075] like Figure 3 As shown, Figure 3 The schematic diagram of the wheel dynamics model provided in the first embodiment of the present application shows the rolling dynamics model of each wheel, which mainly includes the torque T of the driving motor on the wheel, the force F acting on the wheel by the ground x (i.e. tire longitudinal force), R e represents the wheel rolling radius, ω represents the wheel rotation speed, and the wheel dynamics model can be used to calculate the rate of change of the wheel speed. The formula is as follows:

[0076]

[0077] In this model, the total torque T ij The driver's desired torque and the additional torque T ij =T d +ΔT ij The slip rate of each tire is:

[0078]

[0079] 3. The tire model is constructed as follows:

[0080] A nonlinear slip tire model can be used to accurately describe the tire forces. The coupled tire model can be described as follows:

[0081]

[0082] in, represents the critical slip ratio, Indicates the magnitude of the sum of the lateral and longitudinal slip rates, σ x and σ y They represent the theoretical slip rates in the longitudinal and lateral directions respectively, where Fz is the vertical force of the tire in N.

[0083] In this implementation, a reference quantity may be established based on the motion state data and the steering request through the above-mentioned two-degree-of-freedom vehicle dynamics model.

[0084] In a feasible implementation, step S20 of this embodiment may include the steps of: determining the angle at which the driver controls the steering wheel according to the steering request; constructing a reference yaw rate based on the angle of the steering wheel; and generating a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the reference yaw rate.

[0085] It should be noted that the angle at which the driver controls the steering wheel is the above-mentioned front wheel steering angle given by the driver.

[0086] Specifically, based on the above vehicle model, the establishment of the reference quantity may include: in order to ensure the stability of the vehicle, the angle δ of the steering wheel controlled by the driver may be f Construct the reference yaw rate γ * Based on the linear two-degree-of-freedom model, the following reference quantities can be generated:

[0087]

[0088] in:

[0089]

[0090]

[0091] l=l F +l R (7);

[0092]

[0093] Among them, C F is the front wheel cornering stiffness, in N / rad; CR is the rear wheel cornering stiffness, in N / rad.

[0094] Converting equations (6) and (7) into state space equations, we can obtain the following equation:

[0095]

[0096] Step S30: inputting the reference amount and the motion state data into an upper-layer controller to obtain an additional yaw moment, wherein the upper-layer controller is a yaw controller designed by a backstepping nonlinear control method.

[0097] It should be noted that this embodiment adopts a hierarchical control structure, and the upper controller uses the backstepping method to design the yaw controller. Among them, the backstepping nonlinear control method is a control strategy, and its basic idea is to design the controller by step-by-step recursion, starting from the last state equation of the system, designing the virtual control quantity, and then substituting it into the previous state equation, and so on, gradually constructing the entire control law. It can achieve stable control and good performance of nonlinear systems.

[0098] It should be noted that the additional yaw moment is a moment acting on the vehicle, causing the vehicle to generate additional rotation (yaw) motion around the vertical axis. The upper controller will generate an additional yaw torque ΔM.

[0099] In this embodiment, through the upper-level control, the yaw rate can be controlled to track the driver's steering request and stabilize the yaw motion of the vehicle at the same time.

[0100] Step S40: inputting the additional yaw moment and the motion state data into a lower-layer controller to obtain an additional motor torque of the vehicle, wherein the lower-layer controller is a torque controller designed by a wheel dynamics model.

[0101] It should be noted that the additional motor torque (ie, additional motor torque) is the additional torque generated by the motor.

[0102] It should be noted that the lower-level controller controls the vehicle by outputting additional motor torque.

[0103] In this embodiment, for ease of understanding, refer to Figure 4 , Figure 4A control block diagram provided for the first embodiment of the present application. The motion state data of the four-wheel independent drive vehicle and the steering request input by the driver can be obtained first, and then based on the motion state data and the steering request, a reference is established through a two-degree-of-freedom vehicle dynamics model to obtain a reference quantity. Then, a hierarchical control structure is used to control the vehicle. The upper-level control uses the backstepping method to design a yaw controller (i.e., a backstepping controller), which can track the driver's steering request by controlling the yaw angular velocity and stabilize the yaw motion of the vehicle at the same time. The upper-level controller generates additional yaw torque. The lower-level controller uses the above-mentioned wheel dynamics model to design a torque controller (i.e., an optimal controller). The upper-level controller is used as the desired input yaw torque, and the motion state of the wheel and the driver's torque request are used as input. The four wheel-side motors utilize the over-driving characteristics of their system and combine backstepping and quadratic programming (QP) methods to obtain additional motor torque, thereby achieving control of the vehicle.

[0104] In the technical solution provided by this embodiment, the vehicle's motion state data and the steering request input by the driver are first obtained; then, according to the motion state data and the steering request, a reference quantity is established through a two-degree-of-freedom vehicle dynamics model; then, the reference quantity and the motion state data are input into an upper controller to obtain an additional yaw moment, and the upper controller is a yaw controller designed by a backstepping nonlinear control method; finally, the additional yaw moment and the motion state data are input into a lower controller to obtain an additional motor torque of the vehicle, and the lower controller is a torque controller designed by a wheel dynamics model. Since this embodiment combines backstepping and optimization of the upper and lower controllers, the longitudinal and lateral stability of the vehicle can be ensured, the stability of the four-wheel independent drive vehicle under extreme conditions is improved, and the interference with the driver's expectations is reduced.

[0105] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above-mentioned embodiment 1 can be referred to the above introduction, and will not be repeated in the following. Figure 5 , Figure 5 A flow chart of the second embodiment of the vehicle torque distribution control method of the present application.

[0106] Before step S10 of this example, the design of the upper controller includes steps S01 to S03:

[0107] Step S01: Determine the system tracking error of the upper controller.

[0108] It should be noted that the system tracking error is the difference between the desired system output (target value) of the upper controller and the actual system output.

[0109] Step S02: Design the system tracking error according to the Lyapunov function to obtain the upper control law.

[0110] It should be noted that the Lyapunov function is a scalar function used to determine the stability of a dynamic system. By analyzing the properties of this function, such as positive definiteness, negative definiteness, etc., the stability of the system near a certain equilibrium point or state can be determined.

[0111] It should be noted that the upper-level control law is the target setting in the upper-level controller. Figure 4 As shown, the upper layer designs the yaw controller using the backstepping method, aiming to track the driver's steering request by controlling the yaw angular velocity and stabilize the yaw motion of the vehicle at the same time. The upper layer controller will generate an additional yaw torque ΔM.

[0112] Step S03: designing an upper-level controller according to the upper-level control law and the backstepping nonlinear control method.

[0113] Specifically, the design of the upper-level controller includes:

[0114] Assuming that the system is zero dynamic and stable, set the system output y = γ and the reference value y r =γ * The system tracking error is the difference between the actual system output and the reference value, e = y * -y, taking its derivative we get:

[0115]

[0116] Define the Lyapunov function as The derivative is:

[0117]

[0118] The control law is designed as:

[0119]

[0120] Among them, k is the control parameter of the upper controller, which can be obtained The closed-loop system is asymptotically stable.

[0121] In this implementation, the upper controller adopts a backstepping nonlinear control method to minimize the yaw rate tracking error.

[0122] Furthermore, before step S10 of this example, the design of the lower-level controller includes the steps of: determining the rate of change of the wheel speed tracking error of the vehicle according to the wheel dynamics model; designing the rate of change of the wheel speed tracking error according to the Lyapunov function to obtain the lower-level control law; and designing the lower-level controller according to a preset objective function, preset constraints and the lower-level control law.

[0123] It should be noted that the rate of change of the wheel speed tracking error is the speed at which the error between the actual wheel speed value and the expected tracking value changes over time.

[0124] It should be noted that the lower-level control law is the target setting in the lower-level controller, such as Figure 4 As shown in the figure, the lower controller takes the yaw torque as the desired input of the upper controller, and takes the motion state of the wheel and the driver's torque request as input. The four wheel-side motors utilize the over-driving characteristics of the system and combine back-stepping and quadratic programming (QP) methods to obtain additional motor torque to achieve vehicle control.

[0125] In this embodiment, the lower layer torque controller uses the upper layer controller ΔM as the desired input yaw torque, and the wheel motion state and the driver's torque request as input. The four wheel-side motors use the overdrive characteristics of the system and combine backstepping and quadratic programming (QP) methods to obtain additional motor torque ΔT ij , thereby achieving control of the vehicle.

[0126] Specifically, the design of the lower-level controller may include:

[0127] Since the upper controller uses the backstepping method to obtain the additional yaw torque ΔM, the lower controller has two goals: (1) to meet the yaw torque requirements of the upper controller; and (2) to ensure the stability of the longitudinal tire slip rate by properly distributing the motor torque.

[0128] Consider the second goal first. For a single tire, in order to ensure the stability of the longitudinal slip rate, the expected slip rate value κ ij * =0, that is Define the wheel speed tracking error as e ijω =ω ij * -ω ij .

[0129] The rate of change of tracking error can be obtained as:

[0130]

[0131] Similar to the derivation of the upper-level controller, the lower-level control law can be derived as follows:

[0132]

[0133] The derivative of its Lyapunov function with respect to time is also negative definite (the same is true for the derivation process of formulas 10 and 11).

[0134] Among them, the design of the preset objective function is: Objective function: In order to satisfy the yaw moment ΔM of the upper controller * To meet the requirements, it is necessary to control the torque of four independent wheels.

[0135] AΔT=ΔM * (15);

[0136] in:

[0137]

[0138] ΔT=[ΔT FL ,ΔT FR ,ΔT RL ,ΔT RR ] T ;

[0139] The optimization problem in this embodiment involves four objective functions. The preset objective functions include a first objective function J1, a second objective function J2, a third objective function J3, and a fourth objective function J4. First, the equality constraint in formula (15) is not always strictly satisfied, so formula (15) is converted into minimizing J1 = ‖AΔT-ΔM * ‖ 2 , and obtain the first objective function. Secondly, minimize J2 = ‖ΔT‖ 2 The third objective is to minimize J3 = ‖I4ΔT‖ 2 , where I4 = [1 1 1 1], the purpose is to reduce the overall interference to the driver by minimizing the sum of the torques acting on the four wheels, and the third objective function is obtained. The last objective function is the combined minimization of these four objective functions, and the fourth objective function is:

[0140] J = J1 + w2J2 + w3J3;

[0141] Among them, w2 and w3 are optimization weights.

[0142] The preset constraint conditions in this embodiment include a first constraint condition and a second constraint condition. In order to ensure the stability of the slip ratio controller, the feedback coefficient k ij must be positive and remain within a certain threshold range to avoid system oscillation. The first constraint is:

[0143] 0 <k ij,min ≤k ij ≤k ij,max (18);

[0144] Among them, k ij The slip rate of each tire, k ij,minis the minimum value of slip rate, k ij,max is the maximum value of slip rate;

[0145] Secondly, the physical constraints of the motor must be considered, and the maximum value of the additional torque ΔT cannot be exceeded. max , forming the second constraint. The second constraint is:

[0146] |ΔT ij |≤ΔT max (19);

[0147] Where |ΔT ij | is the absolute value of the additional motor torque, ΔT max is the maximum additional motor torque.

[0148] At this time, let the optimization variable definition k = [k FL ,k FR ,k RL ,k RR ], we can get:

[0149]

[0150] in,

[0151] E I =I w diag(e FL ,e FR ,e RL ,e RR ) (twenty one);

[0152]

[0153] The objective function of formula (17) can be transformed into:

[0154] J = k T E I T H T E I k+(2c T T H T E I -2ΔM * AE I )k+c (22);

[0155] Among them, H R =A T A+w2E4+w3I4 T I4. Under the conditions of satisfying formulas (18) and (19), the quadratic programming problem is expressed as:

[0156] min kJ = k T Hk+f T k (23);

[0157] in:

[0158] H T =A T A+w2E4+w3I4 T I4;

[0159] H=E I T H T E I (twenty four);

[0160] f=(2c T T H T E I -2ΔM * AE I ) T ;

[0161] The lower-level controller parameter k can be obtained by solving formula (23), and the additional motor torque ΔT can be obtained according to formula (20), thus achieving a closed-loop control of the vehicle motion.

[0162] In this embodiment, the lower controller combines backstepping with optimization to achieve the desired tire slip ratio while considering the motor torque constraint. The proposed control strategy can meet various requirements, such as ensuring longitudinal and lateral stability, and minimizing interference with driver expectations (such as unexpected acceleration and deceleration).

[0163] In the technical solution provided in this embodiment, in order to minimize the tracking error of the yaw rate, the upper controller adopts a backstepping nonlinear control method. The lower controller takes into account the overdrive characteristics of the four lower motors and proposes a control method that combines backstepping with optimization to track the required tire slip rate while minimizing driver interference and considering limited motor execution. This can meet different requirements such as longitudinal and lateral stability and handling, while reducing interference with driver torque requirements in dangerous situations.

[0164] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the vehicle torque distribution control method of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0165] The present application also provides a vehicle torque distribution control device, please refer to Figure 6 , Figure 6 This is a schematic diagram of the module structure of the vehicle torque distribution control device according to an embodiment of the present application; the vehicle torque distribution control device comprises:

[0166] The data acquisition module 601 is used to acquire the vehicle's motion state data and the steering request input by the driver;

[0167] A reference quantity establishing module 602, configured to establish a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request;

[0168] A yaw moment module 603, used for inputting the reference amount and the motion state data into an upper controller to obtain an additional yaw moment, wherein the upper controller is a yaw controller designed by a backstepping nonlinear control method;

[0169] The torque generation module 604 is used to control the additional yaw moment and the motion state data to be input into a lower-level controller to obtain additional motor torque of the vehicle. The lower-level controller is a torque controller designed by a wheel dynamics model.

[0170] In this embodiment, the reference quantity establishing module 602 is also used to determine the angle of the steering wheel controlled by the driver according to the steering request; construct a reference yaw rate based on the angle of the steering wheel; and generate a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the reference yaw rate.

[0171] Furthermore, the vehicle torque distribution control device also includes a controller design module 605, which is used to determine the system tracking error of the upper-level controller; design the system tracking error according to the Lyapunov function to obtain the upper-level control law; and design the upper-level controller according to the upper-level control law and the backstepping nonlinear control method.

[0172] Furthermore, the controller design module 605 is also used to determine the rate of change of the wheel speed tracking error of the vehicle based on the wheel dynamics model; design the rate of change of the wheel speed tracking error according to the Lyapunov function to obtain the lower-level control law; and design the lower-level controller according to the preset objective function, preset constraints and the lower-level control law.

[0173] Further, in the controller design module 605, the preset objective function includes a first objective function J1, a second objective function J2, a third objective function J3 and a fourth objective function J4;

[0174] The fourth objective function is:

[0175] J = J1 + w2J2 + w3J3;

[0176] Among them, w2 and w3 are optimization weights.

[0177] Further, in the controller design module 605, the preset constraint condition includes a first constraint condition and a second constraint condition;

[0178] The first constraint condition is:

[0179] 0 <k ij,min ≤k ij ≤k ij,max ;

[0180] Among them, k ij The slip rate of each tire, k ij,min is the minimum value of slip rate, k ij,max is the maximum value of slip rate;

[0181] The second constraint is:

[0182] |ΔT ij |≤ΔT max ;

[0183] Where |ΔT ij | is the absolute value of the additional motor torque, ΔT max is the maximum additional motor torque.

[0184] Other embodiments or specific implementations of the vehicle torque distribution control device of the present application can refer to the above-mentioned method embodiments and will not be repeated here.

[0185] The vehicle torque distribution control device provided by the present application adopts the vehicle torque distribution control method in the above embodiment, which can solve the technical problem that the traditional stability control method interferes with the driver's torque demand. Compared with the prior art, the beneficial effects of the vehicle torque distribution control device provided by the present application are the same as the beneficial effects of the vehicle torque distribution control method provided by the above embodiment, and other technical features in the vehicle torque distribution control device are the same as the features disclosed in the above embodiment method, which will not be repeated here.

[0186] The present application also proposes a vehicle, wherein torque distribution is achieved by a vehicle torque distribution control device, the vehicle torque distribution control device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the vehicle torque distribution control method in the above-mentioned embodiment one.

[0187] Reference below Figure 7 , Figure 7The schematic diagram of the device structure of the hardware operating environment involved in the vehicle torque distribution control method in the embodiment of the present application shows a schematic diagram of the structure of the vehicle torque distribution control device suitable for implementing the embodiment of the present application. The vehicle torque distribution control device in the embodiment of the present application may include but is not limited to mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 7 The vehicle torque distribution control device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0188] like Figure 7 As shown, the vehicle torque distribution control device may include a processing device 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the vehicle torque distribution control device are also stored. The processing device 1001, ROM1002, and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the vehicle torque distribution control device to communicate with other devices wirelessly or by wire to exchange data. Although the figure shows a vehicle torque distribution control device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0189] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0190] The vehicle torque distribution control device provided by the present application adopts the vehicle torque distribution control method in the above embodiment, which can solve the technical problem that the traditional stability control method interferes with the driver's torque demand. Compared with the prior art, the beneficial effects of the vehicle torque distribution control device provided by the present application are the same as the beneficial effects of the vehicle torque distribution control method provided by the above embodiment, and the other technical features of the vehicle torque distribution control device are the same as the features disclosed in the method of the previous embodiment, which will not be repeated here.

[0191] It should be understood that the various parts disclosed in this application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0192] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0193] The present application provides a computer-readable storage medium having computer-readable program instructions (ie, computer programs) stored thereon, the computer-readable program instructions being used to execute the vehicle torque distribution control method in the above-mentioned embodiment.

[0194] The computer-readable storage medium provided in the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared or semiconductor systems, systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination of the above.

[0195] The computer-readable storage medium may be included in the vehicle torque distribution control device; or may exist independently without being assembled into the vehicle torque distribution control device.

[0196] The above-mentioned computer-readable storage medium carries one or more programs. When the above-mentioned one or more programs are executed by the vehicle torque distribution control device, the vehicle torque distribution control device: obtains the vehicle's motion state data and the steering request input by the driver; establishes a reference quantity through a two-degree-of-freedom vehicle dynamics model based on the motion state data and the steering request; inputs the reference quantity and the motion state data into an upper-level controller to obtain an additional yaw moment, and the upper-level controller is a yaw controller designed by a backstepping nonlinear control method; inputs the additional yaw moment and the motion state data into a lower-level controller to obtain the vehicle's additional motor torque, and the lower-level controller is a torque controller designed by a wheel dynamics model.

[0197] Computer program code for performing the operations of the present application may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0198] The flowchart and block diagram in the accompanying drawings illustrate the possible architecture, functions and operations of the system, method and computer program product according to various embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0199] The modules involved in the embodiments described in the present application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0200] The readable storage medium provided by the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned vehicle torque distribution control method, and can solve the technical problem that the traditional stability control method interferes with the driver's torque demand. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present application are the same as the beneficial effects of the vehicle torque distribution control method provided by the above-mentioned embodiment, and will not be repeated here.

[0201] The present application also provides a computer program product, comprising a computer program, which implements the steps of the vehicle torque distribution control method as described above when executed by a processor.

[0202] The computer program product provided by the present application can solve the technical problem that the traditional stability control method interferes with the driver's torque demand. Compared with the prior art, the beneficial effects of the computer program product provided by the present application are the same as the beneficial effects of the vehicle torque distribution control method provided by the above embodiment, which will not be repeated here.

[0203] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A vehicle torque distribution control method, It is characterized in that The method includes: Acquire the vehicle's motion state data and the steering request input by the driver; Establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request; Inputting the reference amount and the motion state data into an upper controller to obtain an additional yaw moment, wherein the upper controller is a yaw controller designed by a backstepping nonlinear control method; The additional yaw moment and the motion state data are input into a lower-level controller to obtain an additional motor torque of the vehicle. The lower-level controller is a torque controller designed by a wheel dynamics model.

2. The method according to claim 1, It is characterized in that The step of establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request comprises: determining an angle at which a driver controls a steering wheel according to the steering request; constructing a reference yaw rate based on the angle of the steering wheel; A reference quantity is generated by a two-degree-of-freedom vehicle dynamics model according to the motion state data and the reference yaw angular velocity.

3. The method according to claim 1, It is characterized in that Before the step of obtaining the vehicle's motion state data and the steering request input by the driver, the design of the upper controller includes: Determine the system tracking error of the upper controller; The tracking error of the system is designed according to the Lyapunov function to obtain the upper control law; An upper-level controller is designed according to the upper-level control law and the backstepping nonlinear control method.

4. The method according to any one of claims 1 to 3, It is characterized in that Before the step of obtaining the vehicle's motion state data and the steering request input by the driver, the design of the lower controller includes: Determine the rate of change of the wheel speed tracking error of the vehicle according to the wheel dynamics model; The rate of change of the wheel speed tracking error is designed according to the Lyapunov function to obtain the lower control law; The lower-level controller is designed according to the preset objective function, the preset constraint conditions and the lower-level control law.

5. The method according to claim 4, It is characterized in that The preset objective function includes a first objective function J 1 , the second objective function J 2 , the third objective function J 3 And the fourth objective function J 4 ; The fourth objective function is: J=J 1 +w 2 J 2 +w 3 J 3 ; Among them, w 2 、w 3 To optimize the weight.

6. The method according to claim 5, It is characterized in that The preset constraint condition includes a first constraint condition and a second constraint condition; The first constraint condition is: 0<k ij,min ≤k ij ≤k ij,max ; Among them, k ij The slip rate of each tire, k ij,min is the minimum value of slip rate, k ij,max is the maximum value of slip rate; The second constraint is: |ΔT ij |≤ΔT max ; Where |ΔT ij | is the absolute value of the additional motor torque, ΔT max is the maximum additional motor torque.

7. A vehicle torque distribution control device, It is characterized in that The device comprises: A data acquisition module, used to acquire the vehicle's motion state data and the steering request input by the driver; A reference quantity establishment module, used for establishing a reference quantity through a two-degree-of-freedom vehicle dynamics model according to the motion state data and the steering request; A yaw moment module, used for inputting the reference amount and the motion state data into an upper controller to obtain an additional yaw moment, wherein the upper controller is a yaw controller designed by a backstepping nonlinear control method; The torque generation module is used to control the additional yaw moment and the motion state data to be input into a lower-level controller to obtain additional motor torque of the vehicle. The lower-level controller is a torque controller designed by a wheel dynamics model.

8. A vehicle, It is characterized in that The vehicle executes the steps of implementing the vehicle torque distribution control method according to any one of claims 1 to 6.

9. A storage medium, It is characterized in that The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the vehicle torque distribution control method as described in any one of claims 1 to 6 are implemented.

10. A computer program product, It is characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the vehicle torque distribution control method according to any one of claims 1 to 6 are implemented.

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