Vehicle safety control method, system and equipment and storage medium

Abstract

The invention discloses a vehicle safety control method, system and device and a storage medium, and relates to the technical field of vehicles. The method comprises the following steps: acquiring a current lateral error, a current lateral error change rate, a current course angle error and a current course angle error change rate of a target vehicle; obtaining a target function; the target function is constructed based on the target dynamical model and the target tire model; and according to the current transverse error, the current transverse error change rate, the current course angle error, the current course angle error change rate and the target function, determining a target steering wheel rotation angle and a target longitudinal acceleration of the target vehicle, so as to perform safety control on the target vehicle under the tire burst working condition based on the target steering wheel rotation angle and the target longitudinal acceleration. Longitudinal acceleration input serves as the transverse control quantity, transverse and longitudinal combined control is adopted, the risks of transverse collision and rollover are reduced, and safety control over the vehicle during tire burst is achieved.

Description

Technical Field

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

[0002] Tire blowouts can easily lead to accidents, and since most drivers lack experience in handling tire blowouts while driving, manual handling of tire blowouts poses significant safety risks. The mechanical properties of the tire change dramatically after a blowout, making it difficult for traditional stability control systems, such as the Electronic Stability Control (ESP), to effectively intervene. Therefore, it is necessary to develop a safety control method suitable for tire blowouts. Summary of the Invention

[0003] Purpose of the invention: The embodiments of the present application provide a vehicle safety control method, system, device and storage medium to achieve safe and reliable control of a vehicle when a tire blows out.

[0004] Technical solution: A vehicle safety control method described in an embodiment of the present application includes:

[0005] Obtain the current lateral error, current lateral error change rate, current heading angle error, and current heading angle error change rate of the target vehicle;

[0006] Obtaining an objective function; wherein the objective function is constructed based on a target dynamics model and a target tire model; the target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle under a tire blowout condition, and the target tire model is a tire model of the target vehicle under the tire blowout condition;

[0007] A target steering wheel angle and a target longitudinal acceleration of the target vehicle are determined according to the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error change rate, and the objective function, so as to safely control the target vehicle in the tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration.

[0008] In some embodiments, the method for obtaining the objective function includes:

[0009] Constructing an error model of the target vehicle; wherein the state variables of the error model include lateral error, heading angle error, lateral error change rate, and heading angle error change rate;

[0010] determining a state space equation of the error model according to the target dynamics model, the target tire model, and the error model;

[0011] The objective function is constructed according to the state-space equation.

[0012] In some embodiments, determining the state space equation of the error model according to the target dynamics model, the target tire model, and the error model includes:

[0013] Substituting the error model into the target dynamics model to obtain an intermediate model;

[0014] The target tire model is substituted into the intermediate model to obtain the state space equation.

[0015] In some embodiments, the method of determining the target kinetic model includes:

[0016] Constructing a two-degree-of-freedom dynamic model of the target vehicle;

[0017] Determining a target lateral force, a target yaw moment, and a target slip angle of the target vehicle; wherein the target lateral force is the lateral force generated by the unbalanced braking force of the target vehicle in the tire blowout condition; the target yaw moment is the yaw moment generated by the unbalanced braking force of the target vehicle in the tire blowout condition; and the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle;

[0018] The target dynamics model is determined according to the target lateral force, the target yaw moment, the two-degree-of-freedom dynamics model, and the target slip angle.

[0019] In some embodiments, the method of determining the target lateral force and the target yaw moment includes:

[0020] Obtaining a current rotation angle of the flat tire of the target vehicle and a current longitudinal acceleration of the target vehicle;

[0021] Determining the target lateral force according to the structural parameters of the target vehicle, the current rotation angle of the flat tire, and a preset linear coefficient;

[0022] The target yaw moment is determined according to structural parameters of the target vehicle, a current rotation angle of the flat tire, the preset linear coefficient, and the current longitudinal acceleration.

[0023] In some embodiments, the method for determining the target tire model includes:

[0024] Determining a target cornering force and a target slip angle of the target vehicle; wherein the target cornering force includes a front wheel cornering force and a rear wheel cornering force of the target vehicle; and the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle;

[0025] The target tire model is determined according to the target slip angle, the target cornering force, and a preset tire blowout correction coefficient.

[0026] In some embodiments, constructing the objective function according to the state-space equation includes:

[0027] Discretizing the state-space equation to obtain a recursively expressed state-space equation;

[0028] A quadratic objective function is constructed according to the recursively expressed state-space equation.

[0029] Accordingly, an embodiment of the present application further provides a vehicle safety control system, including:

[0030] The first acquisition module is used to obtain the current lateral error, the current lateral error change rate, the current heading angle error and the current heading angle error change rate of the target vehicle;

[0031] a second acquisition module, configured to acquire an objective function; wherein the objective function is constructed based on a target dynamics model and a target tire model; the target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle under a tire blowout condition, and the target tire model is a tire model of the target vehicle under the tire blowout condition;

[0032] a determination module, configured to determine a target steering wheel angle and a target longitudinal acceleration of the target vehicle based on the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error change rate, and the objective function, so as to safely control the target vehicle in the tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration.

[0033] Correspondingly, an embodiment of the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the vehicle safety control method as described above when executing the computer program.

[0034] Accordingly, an embodiment of the present application further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the vehicle safety control method as described above is implemented.

[0035] Beneficial effect: Compared with the prior art, the vehicle safety control method, system, device and storage medium of the embodiments of the present application, the vehicle safety control method includes: obtaining the current lateral error, the current lateral error change rate, the current heading angle error and the current heading angle error change rate of the target vehicle; obtaining the objective function; wherein the objective function is constructed based on the target dynamics model and the target tire model; the target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle in a tire blowout condition, and the target tire model is a tire model of the target vehicle in a tire blowout condition; according to the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error and the objective function, the target steering wheel angle and the target longitudinal acceleration of the target vehicle are determined, so as to safely control the target vehicle in the tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration. The vehicle safety control method provided in this application constructs a dynamic model and a tire model of a tire blowout condition, and constructs an objective function based on the dynamic model and the tire model of the tire blowout condition. The objective function is used to determine the steering wheel angle and longitudinal acceleration for safe control of the vehicle under the tire blowout condition, and the longitudinal acceleration is input as the lateral control variable. Combined lateral and longitudinal control is adopted to reduce the risk of lateral collision and rollover, thereby achieving safe and reliable control of the vehicle in the event of a tire blowout. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 is a flow chart of a vehicle safety control method provided in an embodiment of the present application;

[0038] Figure 2 Schematic diagram of the structure of the two-degree-of-freedom dynamic model of the target vehicle provided in the embodiment of the present application;

[0039] Figure 3 This is a schematic diagram of the force on the target vehicle wheel under a left front tire blowout condition provided in an embodiment of the present application;

[0040] Figure 4 This is a schematic diagram of the safety control principle structure of a vehicle provided in an embodiment of the present application;

[0041] Figure 5 This is a block diagram of the principle structure of a vehicle safety control system provided in an embodiment of the present application;

[0042] Figure 6 It is a structural diagram of an electronic device provided in an embodiment of the present application.

[0043] Reference numerals:

[0044] 101 - first acquisition module; 102 - second acquisition module; 103 - determination module; 100 - vehicle safety control system. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0046] It should be understood that although the terms first, second, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another. Thus, the first component discussed below could be referred to as the second component without departing from the teachings of the present invention. As used herein, the term "and / or" includes any one and all combinations of one or more of the associated listed items.

[0047] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of exemplary embodiments and may not be to scale. The modules or processes in the drawings are not necessarily required to implement the present application and therefore cannot be used to limit the scope of protection of the present application.

[0048] The applicant's research has found that over 7% of high-speed accidents are caused by tire blowouts. When a vehicle is traveling at 120 km / h, the fatality rate of a tire blowout is as high as 80% to 100%. Most drivers lack experience in handling tire blowouts while driving, and manual handling of tire blowouts poses significant safety risks. The mechanical properties of a tire change dramatically after a blowout, making it difficult for traditional stability control systems (such as Electronic Stability Control (ESP)) to effectively intervene.

[0049] Related technologies fall into two main categories: one is passive safety technology, employing run-flat tires. The principle behind this approach is to strengthen the sidewall structure, allowing the vehicle to continue driving for a short distance even after a tire blowout. However, this approach has the disadvantages of high cost and inability to address the dynamic instability associated with a tire blowout. The other is primary active control technology, employing ESP basic braking intervention. This approach involves applying unilateral braking upon detecting an abnormal wheel speed. However, its disadvantages include a single control strategy and a tendency to experience secondary loss of control at high speeds.

[0050] For example, patent JP2018114882A (Chinese equivalent CN110341692A) discloses an electronic power steering (EPS) reverse torque compensation method that dynamically adjusts the steering assist to offset the "rudder drag effect" caused by a tire blowout. However, this invention suffers from a significant reduction in compensation effectiveness when the rear tire blows out.

[0051] For example, patent US20190283745A1 (Chinese equivalent patent CN110316216A) discloses a steering angle correction algorithm based on real-time estimation of cornering stiffness, which solves the problem of inaccurate tire force modeling after a tire blowout. However, this invention relies on a high-precision steering wheel torque sensor, which has high hardware costs.

[0052] For example, patent US20210094461A1 (Chinese equivalent patent CN112758112A) discloses a method for dynamically distributing torque across four independent motors, achieving stability control by reducing torque on wheels with flat tires and increasing torque on wheels with non-flat tires. However, this invention suffers from insufficient torque adjustment margin when the battery SOC is low.

[0053] For example, patent EP2895366B1 (Chinese equivalent patent CN103946087A) discloses a control strategy for prioritizing braking on the rear wheel on the side with the non-flat tire. This strategy utilizes differential braking to quickly compensate for yaw torque after a tire blowout. However, this invention suffers from the disadvantage of excessive braking intervention at low speeds, which can cause the vehicle to stall.

[0054] For example, patent CN111624462A discloses a three-system collaborative control architecture for braking, steering, and suspension, which achieves full operating condition adaptation through hierarchical decision-making. However, this invention suffers from the drawbacks of complex system calibration and difficulty ensuring consistency in mass production.

[0055] In view of this, the embodiments of the present application provide a vehicle safety control method, system, device and storage medium. The present application constructs a dynamic model and a tire model of a tire blowout condition, and constructs an objective function based on the dynamic model and the tire model of the tire blowout condition, so as to determine the vehicle's safe control steering wheel angle and longitudinal acceleration under the tire blowout condition through the objective function, input the longitudinal acceleration as the lateral control quantity, and adopt joint lateral and longitudinal control to reduce the risk of lateral collision and rollover, thereby achieving safe and reliable control of the vehicle in the event of a tire blowout.

[0056] Figure 1This is a flow chart of a vehicle safety control method provided in an embodiment of the present application. This method can be applied to a vehicle control system to achieve safe and reliable control of a vehicle tire blowout. This method can be executed by a vehicle safety control system, which can be implemented by software and / or hardware and can be configured in a processor or controller of the vehicle control system. Figure 1 , the method comprises the following steps:

[0057] Step 110: Obtain the current lateral error, the current lateral error change rate, the current heading angle error, and the current heading angle error change rate of the target vehicle.

[0058] Among them, the current lateral error, the current lateral error change rate, the current heading angle error and the current heading angle error change rate can be calculated in real time through the error model of the target vehicle.

[0059] Step 120: Obtain the objective function.

[0060] Among them, the objective function is constructed based on the target dynamics model and the target tire model.

[0061] The target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle under a tire blowout condition, and the target tire model is a tire model of the target vehicle under a tire blowout condition.

[0062] First, a simplified two-degree-of-freedom dynamic model of the target vehicle is established. Figure 2 Schematic diagram of the structure of the target vehicle two-degree-of-freedom dynamic model provided in the embodiment of the present application. Figure 2 , the dynamic equation is established as follows:

[0063] ma x =F xf sinδ f +F xr ;

[0064] ma y =F yf cosδ f +F yr ;

[0065]

[0066] For example, in the technical solution of the embodiment of the present application, the “lateral direction” of the target vehicle refers to the vehicle body coordinate system (such as Figure 2 “Longitudinal” refers to the X-axis direction of the vehicle body coordinate system, and “longitudinal” refers to the Y-axis direction of the vehicle body coordinate system.

[0067] Where m represents the mass of the target vehicle; I z represents the moment of inertia of the target vehicle; Indicates the yaw acceleration of the target vehicle; a x Indicates the longitudinal acceleration of the target vehicle; a y Indicates the lateral acceleration of the target vehicle; F xf Indicates the lateral force on the front wheel of the target vehicle; δ f Indicates the front wheel turning angle of the target vehicle; F xr Indicates the lateral force exerted on the rear wheels of the target vehicle; F yf Indicates the front wheel cornering force of the target vehicle; F yr represents the rear wheel cornering force of the target vehicle; a represents the distance from the center of mass of the target vehicle to the front axle; b represents the distance from the center of mass of the target vehicle to the rear axle; v x represents the longitudinal velocity of the target vehicle in the ego vehicle coordinate system, v y represents the lateral velocity of the target vehicle in the ego vehicle coordinate system; α f represents the front wheel slip angle of the target vehicle, α r represents the rear wheel slip angle of the target vehicle, and represents the center of mass slip angle of the target vehicle.

[0068] In some embodiments, the method for obtaining the objective function includes the following steps:

[0069] The first step is to construct an error model of the target vehicle; wherein the state quantities of the error model include lateral error, heading angle error, lateral error change rate and heading angle error change rate.

[0070] Specifically, the error model is established as follows:

[0071] Let the lateral error be e d , we can get:

[0072]

[0073] in, Indicates the rate of change of lateral error; The rate of change that represents the rate of change of the lateral error; represents the rate of change of the expected value of the heading angle given on the target vehicle trajectory; a ydes Represents the expected value of the lateral acceleration given the target vehicle trajectory.

[0074] The heading angle error is We can get:

[0075]

[0076] in, Indicates the rate of change of heading angle error; The rate of change that represents the rate of change of the heading angle error; The rate of change that represents the rate of change of the desired value of the heading angle given the target vehicle trajectory.

[0077] The second step is to determine the state space equation of the error model based on the target dynamics model, target tire model and error model.

[0078] In some embodiments, a method for determining a target dynamic model includes: constructing a two-degree-of-freedom dynamic model of a target vehicle; determining a target lateral force, a target yaw moment, and a target slip angle of the target vehicle; wherein the target lateral force is the lateral force generated by the unbalanced braking force of the target vehicle in a tire blowout condition; the target yaw moment is the yaw moment generated by the unbalanced braking force of the target vehicle in a tire blowout condition; the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle; and determining the target dynamic model based on the target lateral force, the target yaw moment, the two-degree-of-freedom dynamic model, and the target slip angle.

[0079] Among them, the two-degree-of-freedom dynamic model of the target vehicle is as follows: Figure 2 Specifically, according to Figure 2 From the two-degree-of-freedom dynamic model and dynamic equation, we can know that the lateral acceleration a y Can be decomposed into the acceleration caused by lateral displacement and centripetal acceleration The details are as follows:

[0080]

[0081] in, represents the yaw angle of the target vehicle, Indicates the yaw rate of the target vehicle.

[0082] According to the cornering characteristics of the target vehicle tire, the front wheel cornering force F yf and rear wheel cornering force F yr They can be expressed as:

[0083] F yf =C f (-δ f +θ vf );

[0084] F yr =C r θ vr ;

[0085] Among them, θ vf Represents the front wheel slip angle, that is, the angle between the front wheel movement direction and the tire cross section; θ vr Represents the rear wheel slip angle, that is, the angle between the rear wheel movement direction and the tire cross section; C f Indicates the cornering stiffness of the front wheel, C rIndicates the cornering stiffness of the rear wheel.

[0086] Linear optimization of the slip angle: Since the slip angle is small, it can be approximately considered that the linearly optimized front wheel slip angle and rear wheel slip angle (i.e., target slip angle) are:

[0087]

[0088] Assume that the front wheel turning angle is small, that is, cosδ f =1.

[0089] Specifically, the two-degree-of-freedom dynamic model of the target vehicle under a tire blowout condition is modified: Since the core treatment measure for a tire blowout is to stabilize the vehicle and gradually slow it down to a stop, only braking control is performed in the longitudinal direction without driving control. After a tire blowout, the braking force of the blown tire is much smaller than that of the brake wheel. Therefore, when the braking force is applied, the sideways force and torque opposite to the blown tire will be generated on the vehicle due to the difference in braking force on both sides. Therefore, the dynamic model is linearly modified (i.e., the target dynamic model) to:

[0090] ma y =F yf +F yr +F by ;

[0091]

[0092] Among them, F by Indicates the lateral force generated by the unbalanced braking force, M b Indicates the yaw moment caused by unbalanced braking force.

[0093] The dynamic model provided in the embodiment of the present application can improve the accuracy of the dynamic model by introducing the tire blowout correction coefficient, the lateral force generated by the unbalanced braking force, and the yaw moment generated by the unbalanced braking force, thereby improving the accuracy of the subsequent state-space equations and objective functions, and thus facilitating the safe and reliable control of vehicles with tire blowouts.

[0094] In some embodiments, the method for determining the target lateral force and the target yaw moment includes: obtaining the current rotation angle of the flat tire of the target vehicle and the current longitudinal acceleration of the target vehicle; determining the target lateral force based on the structural parameters of the target vehicle, the current rotation angle of the flat tire and a preset linear coefficient; and determining the target yaw moment based on the structural parameters of the target vehicle, the current rotation angle of the flat tire, the preset linear coefficient and the current longitudinal acceleration.

[0095] For example, the left front wheel of the target vehicle is a flat tire. Figure 3 This is a schematic diagram of the force on the target vehicle wheel under the left front tire blowout condition provided in the embodiment of this application. Figure 3 , Fb represents the braking force of the normal wheel, d represents the distance from the center of mass of the target vehicle to the wheel in the y-axis direction, and it is approximately assumed that the distance from the center of mass to the left and right sides is the same.

[0096] According to the National Highway Traffic Safety Administration (NHTSA) test, after a tire blows out, the braking force of the tire drops to 10% to 20% of the normal value. For example, in the technical solution of the embodiment of the present application, 10% is taken (the smaller value is taken to neutralize cosδ f This paper takes the loss of accuracy caused by linearization as an example to illustrate.

[0097] For example, see Figure 3 , the longitudinal dynamic equation is established based on the braking force on the four tires as follows:

[0098] ma x =(1+10%)F b cosδ f +2F b ;

[0099] After the longitudinal dynamic equation is shifted, we can get:

[0100]

[0101] The lateral force generated by the unbalanced braking force is:

[0102]

[0103] The yaw moment generated by the unbalanced braking force is:

[0104]

[0105] Since the front wheel turning angle is small, sinδ f Linearization to δ f , cosδ f If linearized to 1, the lateral force and yaw moment generated by the above unbalanced braking force can be rewritten as:

[0106]

[0107] Among them, C k is the preset linear coefficient. C k is a constant. When the left wheel (including the left front wheel and the left rear wheel) has a tire blowout, When the right wheel (including the right front wheel and the right rear wheel) has a tire blowout,

[0108] Furthermore, for Fby and M b Since the front wheel turning angle is small, it is not advisable to decelerate suddenly under the tire blowout condition. f =0,a x = -1 is used as an approximate point for linearization, as follows:

[0109] F by About δ f Taking partial derivatives we get:

[0110]

[0111] F by About a x Taking partial derivatives we get:

[0112]

[0113] In δ f =0,a x =-1 calculation:

[0114]

[0115] In δ f =0,a x =-1 for F by Taylor expansion can be performed to obtain the target lateral force:

[0116]

[0117] To M b About δ f Taking partial derivatives we get:

[0118]

[0119] To M b About a x Taking partial derivatives we get:

[0120]

[0121] In δ f =0,a x =-1 calculation:

[0122]

[0123] In δ f =0,a x =-1 place M b Taylor expansion of the target yaw moment is:

[0124]

[0125] In some embodiments, a method for determining a target tire model includes: determining a target cornering force and a target slip angle of a target vehicle; wherein the target cornering force includes a front wheel cornering force and a rear wheel cornering force of the target vehicle; and the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle; and determining the target tire model based on the target slip angle, the target cornering force, and a preset tire blowout correction coefficient.

[0126] The target cornering force and target slip angle are determined according to the aforementioned method, namely:

[0127] Front wheel cornering force F yf and rear wheel cornering force F yr They can be expressed as:

[0128] F yf =C f (-δ f +θ vf );

[0129] F yr =C r θ vr ;

[0130] The linearly optimized front wheel slip angle and rear wheel slip angle (i.e., target slip angle) are:

[0131]

[0132]

[0133] Assume that the front wheel turning angle is small, that is, cosδ f =1.

[0134] Among them, the preset tire blowout correction coefficient includes the front tire blowout correction coefficient μ f and rear tire blowout correction coefficient μ r .

[0135] Among them, the tire cornering stiffness of the target vehicle changes after a tire blowout occurs, and the tire blowout correction coefficient μ is introduced f and μ r Correcting the tire's cornering stiffness. A normal tire (i.e., one that hasn't blown out) has a correction factor of 1. Literature indicates that after a complete blowout, the cornering stiffness is reduced to 1 / 4 of its original value. (Reference: Vehicle Dynamics and Active Safety Control of Tire Blowouts). The correction factor for a blown tire can be dynamically adjusted between 1 and 1 / 4 by monitoring tire pressure.

[0136] Specifically, the preset tire blowout correction coefficient is substituted into the calculation formula of the target cornering force, that is, the front tire blowout correction coefficient μ f Substitute into the calculation formula of the front wheel cornering force, and the rear wheel tire blowout correction coefficient μ rSubstitute the target slip angle into the formula for calculating the rear wheel cornering force. Substitute the target slip angle into the formula for calculating the target cornering force. That is, substitute the linearly optimized front wheel slip angle into the formula for calculating the front wheel cornering force, and substitute the linearly optimized rear wheel slip angle into the formula for calculating the rear wheel cornering force. The target tire model can be obtained as follows:

[0137]

[0138] In some embodiments, determining the state space equation of the error model based on the target dynamics model, the target tire model, and the error model includes: substituting the error model into the target dynamics model to obtain an intermediate model; and substituting the target tire model into the intermediate model to obtain the state space equation.

[0139] Specifically, the error model is substituted into the target dynamics model to obtain the intermediate model:

[0140]

[0141] Then, the target tire model is substituted into the above intermediate model and the state space equation of the error model of the tire blowout vehicle is obtained as follows:

[0142]

[0143] The third step is to construct the objective function based on the state space equation.

[0144] In some embodiments, constructing an objective function based on a state-space equation includes: discretizing the state-space equation to obtain a recursively expressed state-space equation; and constructing a quadratic objective function based on the recursively expressed state-space equation.

[0145] Specifically, the state space equation of the above error model is written as:

[0146]

[0147] in:

[0148]

[0149] After completing the discretization of the vehicle state transition in the above formula, the vehicle state can be recursively expressed as:

[0150]

[0151] Among them, x t+1 Indicates the state at the next moment; represents the state change rate; Δt represents the discrete time interval; I represents the identity matrix; x t Indicates the current state; u tRepresents the input at the current moment; x t is the discretized expression of X, which is the same as X; u t is the discretized expression of U, and its expression is the same as U.

[0152] It can be seen from the above state space equation that the lateral error and the heading error can characterize the collision risk of the vehicle under tire blowout conditions, and the lateral error change rate and the heading error change rate can characterize the rollover risk of the vehicle under tire blowout conditions. Therefore, these four errors are used as state quantities. Since the lateral collision risk and rollover risk of the vehicle are high when a tire blows out, the error model of the embodiment of the present application does not consider the longitudinal performance. However, the embodiment of the present application uses the longitudinal input longitudinal acceleration a x It is used to control lateral characteristics and increase the ability to control lateral forces (rollover and lateral collision) during a tire blowout, thereby improving the safe and reliable control of the target vehicle under tire blowout conditions. Especially under tire blowout conditions, the rolling resistance of the tire with the blowout increases sharply, thereby generating a torsional torque on the center of mass of the vehicle. This interfering torque can easily cause lateral control overshoot and oscillation. Compared with the related art method of using only the steering wheel to control the lateral state, the technical solution of the embodiment of the present application can effectively reduce the risk of vehicle swerving or even lateral collision by jointly controlling the lateral characteristics through the steering wheel angle and longitudinal acceleration.

[0153] The essence of model predictive control is to solve the quadratic optimal problem within the constraints. Let the prediction step of the model predictive control algorithm be N p , then the following quadratic objective function is constructed based on the recursive state space equation:

[0154]

[0155] stx(i+1|k)=Ax(i|k)+Bu(k),i=0,1,...N p ;

[0156] x(0|k)=x(k);

[0157] Among them, x(i+1|k) represents the predicted state of the i+1th step obtained based on the system dynamics model at the current time k; u(k+i) represents the system input of the i-th step at the current time k; A and B are the two matrices in the state space equation; x(0|k) represents the predicted state of the 0th step at the current time k; and x(k) represents the state at the current time k.

[0158] The cost function (i.e., objective function) consists of a tracking error term (i.e., x(i+1|k)) and a control constraint term (i.e., u(k+i)). The corresponding weight matrices are semi-positive definite matrices Q and R, respectively. By adjusting the weight matrices, the risk of lateral collision and rollover can be reduced. For example, increasing R can improve steering stability and prevent sudden steering turns from causing a rollover. The value of R ranges from [2, 2].

[0159] Step 130: Determine a target steering wheel angle and a target longitudinal acceleration of the target vehicle based on the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error change rate, and the objective function, so as to safely control the target vehicle in a tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration.

[0160] The target steering wheel angle is used to characterize the safety control angle of the target vehicle in a tire blowout condition, and the target longitudinal acceleration is used to characterize the safety control acceleration of the target vehicle in a tire blowout condition.

[0161] Design the following boundary constraints for the objective function:

[0162]

[0163] Among them, x i Represents the current state, that is, the four errors in the state space equation (lateral error, heading error, lateral error change rate, and heading error change rate); x min Represents x i The minimum boundary value of x max Represents x i The maximum boundary value of .

[0164] Among them, u i Represents the current input, namely the acceleration provided by the steering wheel angle and the accelerator and brake (i.e. the composite acceleration of the target longitudinal acceleration and lateral acceleration); u min Indicates u i The minimum boundary value of u max Indicates u i The maximum boundary value of .

[0165] Among them, when u max When (2) = 0, the vehicle is prevented from accelerating by limiting the longitudinal acceleration to no more than 0.

[0166] When u min (2)>T abs When the maximum longitudinal deceleration value is limited, the wheels are prevented from locking. abs This is the Anti-lock Braking System (ABS) trigger threshold.

[0167] x min and x max Updates in real time based on the detected road edge to prevent curb collisions.

[0168] Specifically, assuming that the target vehicle currently has a tire blowout, the current lateral error, the current lateral error rate of change, the current heading error, and the current heading error rate of change are obtained. Substituting the current lateral error, the current lateral error rate of change, the current heading error, and the current heading error rate of change into the objective function yields the target steering wheel angle and target longitudinal acceleration for the vehicle with the tire blowout. The steering wheel angle of the vehicle with the tire blowout is then controlled based on the target steering wheel angle, and the acceleration of the vehicle with the tire blowout is controlled based on the target longitudinal acceleration. By using the steering wheel angle and longitudinal acceleration as safety control inputs for the vehicle with the tire blowout, the ability to control lateral forces (rollover and lateral collision) during a tire blowout can be enhanced, achieving safe and reliable control of the vehicle with the tire blowout.

[0169] Furthermore, the technical solution of the present application improves the accuracy of the dynamic model by introducing a tire blowout correction coefficient, lateral force generated by unbalanced braking force, and yaw moment generated by unbalanced braking force into the target dynamic model. By using the longitudinal input (i.e., longitudinal acceleration) as the lateral control variable, a combined lateral and longitudinal control is adopted to reduce the risk of lateral collision and rollover. The design of boundary constraints can avoid longitudinal acceleration of the vehicle or wheel locking. The design can be adjusted to prevent the vehicle from rolling over due to sudden steering.

[0170] Figure 4 This is a schematic diagram of the safety control principle structure of a vehicle provided in an embodiment of the present application. For example, at the current time k, based on the objective function and boundary constraints obtained in the previous steps, the minimization problem is solved, and the first value of the obtained optimal control quantity sequence is applied to the vehicle control system to achieve the combined control of the steering wheel and brake system for vehicle stability in the event of a tire blowout. Figure 4 , the specific implementation process of vehicle stability control is as follows:

[0171] The first step is to determine whether to enter active safety control based on tire pressure changes, and determine the preset linear coefficient C based on the position of the flat tire. k symbol.

[0172] The second step is to establish a two-degree-of-freedom vehicle dynamics model and construct a target dynamics model considering the changes in tire stiffness and braking force after a tire blowout.

[0173] The third step is to obtain the expected motion state of the vehicle based on the matching trajectory points on the planned trajectory.

[0174] Step 4: Calculate the control error x(k) based on the desired vehicle motion state and the current actual vehicle state.

[0175] Step 5: Input the control error and the set boundary constraints into the Model Predictive Control (MPC) controller to solve the optimal control variable u(k) online to control the actual vehicle.

[0176] In summary, compared to related technologies that use a two-degree-of-freedom vehicle dynamics model, the present invention's technical solution is more applicable to the safety control of vehicles with tire blowouts. By linearizing and correcting the two-degree-of-freedom vehicle dynamics model, the present invention proposes a stability control method for vehicles with tire blowouts that does not require additional computing power. Furthermore, the present invention's technical solution is simple and easy to implement, does not increase computing power, and is feasible for mass production.

[0177] Compared with the related art which adopts a single control strategy, the technical solution of the present application adopts a comprehensive control strategy of steering wheel angle and longitudinal acceleration to coordinate steering and braking to regulate vehicle stability.

[0178] Compared with related technologies that use control methods such as Proportional-Integral-Derivative (PID) and Linear Quadratic Regulator (LQR), the technical solution of this application is able to suppress sensor noise through rolling optimization, has multi-variable collaborative optimization capabilities, comprehensively considers lateral collision and rollover risks, and avoids vehicle braking lock, sudden steering, etc. through boundary condition constraints.

[0179] Figure 5 This is a principle structure diagram of a vehicle safety control system provided in the embodiment of the present application. Correspondingly, the embodiment of the present application also provides a vehicle safety control system, please refer to Figure 5 The vehicle safety control system 100 includes: a first acquisition module 101, used to obtain the current lateral error, the current lateral error change rate, the current heading angle error, and the current heading angle error change rate of the target vehicle; a second acquisition module 102, used to obtain the target function; wherein the target function is constructed based on the target dynamics model and the target tire model; the target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle under a tire blowout condition, and the target tire model is a tire model of the target vehicle under a tire blowout condition; a determination module 103, used to determine the target steering wheel angle and target longitudinal acceleration of the target vehicle according to the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error change rate, and the target function, so as to safely control the target vehicle under the tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration.

[0180] The technical solution of the embodiment of the present application provides a vehicle safety control system. By constructing a dynamic model and a tire model of a tire blowout condition, and constructing an objective function based on the dynamic model and the tire model of the tire blowout condition, the objective function is used to determine the steering wheel angle and longitudinal acceleration for safe control of the vehicle under the tire blowout condition. The longitudinal acceleration is input as the lateral control variable, and combined lateral and longitudinal control is adopted to reduce the risk of lateral collision and rollover, thereby achieving safe and reliable control of the vehicle in the event of a tire blowout.

[0181] In some embodiments, the second acquisition module 102 is also used to: construct an error model of the target vehicle; wherein the state quantities of the error model include lateral error, heading angle error, lateral error change rate and heading angle error change rate; determine the state space equation of the error model based on the target dynamic model, the target tire model and the error model; and construct the objective function based on the state space equation.

[0182] In some embodiments, the second acquisition module 102 is further configured to: bring the error model into the target dynamics model to obtain an intermediate model; and bring the target tire model into the intermediate model to obtain a state space equation.

[0183] In some embodiments, the second acquisition module 102 is further used to: construct a two-degree-of-freedom dynamic model of the target vehicle; determine a target lateral force, a target yaw moment, and a target slip angle of the target vehicle; wherein the target lateral force is the lateral force generated by the unbalanced braking force of the target vehicle in a tire blowout condition; the target yaw moment is the yaw moment generated by the unbalanced braking force of the target vehicle in a tire blowout condition; the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle; and determine the target dynamic model based on the target lateral force, the target yaw moment, the two-degree-of-freedom dynamic model, and the target slip angle.

[0184] In some embodiments, the second acquisition module 102 is further used to: obtain the current rotation angle of the flat tire of the target vehicle and the current longitudinal acceleration of the target vehicle; determine the target lateral force based on the structural parameters of the target vehicle, the current rotation angle of the flat tire and the preset linear coefficient; determine the target yaw moment based on the structural parameters of the target vehicle, the current rotation angle of the flat tire, the preset linear coefficient and the current longitudinal acceleration.

[0185] In some embodiments, the second acquisition module 102 is further configured to: determine a target cornering force and a target slip angle of the target vehicle; wherein the target cornering force includes the front wheel cornering force and the rear wheel cornering force of the target vehicle; and the target slip angle includes the linearly optimized front wheel slip angle and the rear wheel slip angle; and determine a target tire model based on the target slip angle, the target cornering force, and a preset tire blowout correction coefficient.

[0186] In some embodiments, the second acquisition module 102 is further configured to: discretize the state-space equation to obtain a recursively expressed state-space equation; and construct a quadratic objective function based on the recursively expressed state-space equation.

[0187] Figure 6 Schematic diagram of the structure of an electronic device provided in the embodiment of the present application. Correspondingly, the embodiment of the present application also provides an electronic device, please refer to Figure 6 The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the vehicle safety control method described above are implemented. Since the vehicle safety control method has been described in detail above, it will not be repeated here.

[0188] Accordingly, an embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-mentioned vehicle safety control method. Since the vehicle safety control method has been described in detail above, it will not be repeated here.

[0189] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0190] The above is a detailed introduction to the vehicle safety control method, system, device and storage medium provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A vehicle safety control method, characterized in that: include: Obtain the current lateral error, current lateral error change rate, current heading angle error, and current heading angle error change rate of the target vehicle; Obtaining an objective function; wherein the objective function is constructed based on a target dynamics model and a target tire model; the target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle under a tire blowout condition, and the target tire model is a tire model of the target vehicle under the tire blowout condition; A target steering wheel angle and a target longitudinal acceleration of the target vehicle are determined according to the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error change rate, and the objective function, so as to safely control the target vehicle in the tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration.

2. The vehicle safety control method according to claim 1, characterized in that: The method for obtaining the objective function includes: Constructing an error model of the target vehicle; wherein the state variables of the error model include lateral error, heading angle error, lateral error change rate, and heading angle error change rate; determining a state space equation of the error model according to the target dynamics model, the target tire model, and the error model; The objective function is constructed according to the state-space equation.

3. The vehicle safety control method according to claim 2, characterized in that: The determining of the state space equation of the error model according to the target dynamics model, the target tire model, and the error model includes: Substituting the error model into the target dynamics model to obtain an intermediate model; The target tire model is substituted into the intermediate model to obtain the state space equation.

4. The vehicle safety control method according to claim 2, characterized in that: The method for determining the target dynamic model includes: Constructing a two-degree-of-freedom dynamic model of the target vehicle; Determining a target lateral force, a target yaw moment, and a target slip angle of the target vehicle; wherein the target lateral force is the lateral force generated by the unbalanced braking force of the target vehicle in the tire blowout condition; the target yaw moment is the yaw moment generated by the unbalanced braking force of the target vehicle in the tire blowout condition; and the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle; The target dynamics model is determined according to the target lateral force, the target yaw moment, the two-degree-of-freedom dynamics model, and the target slip angle.

5. The vehicle safety control method according to claim 4, characterized in that: The method for determining the target lateral force and the target yaw moment includes: Obtaining a current rotation angle of the flat tire of the target vehicle and a current longitudinal acceleration of the target vehicle; Determining the target lateral force according to the structural parameters of the target vehicle, the current rotation angle of the flat tire, and a preset linear coefficient; The target yaw moment is determined according to structural parameters of the target vehicle, a current rotation angle of the flat tire, the preset linear coefficient, and the current longitudinal acceleration.

6. The vehicle safety control method according to claim 2, characterized in that: The method for determining the target tire model includes: Determining a target cornering force and a target slip angle of the target vehicle; wherein the target cornering force includes a front wheel cornering force and a rear wheel cornering force of the target vehicle; and the target slip angle includes a linearly optimized front wheel slip angle and a rear wheel slip angle; The target tire model is determined according to the target slip angle, the target cornering force, and a preset tire blowout correction coefficient.

7. The vehicle safety control method according to claim 2, characterized in that: The constructing the objective function according to the state-space equation comprises: Discretizing the state-space equation to obtain a recursively expressed state-space equation; A quadratic objective function is constructed according to the recursively expressed state-space equation.

8. A vehicle safety control system, characterized in that: include: The first acquisition module is used to obtain the current lateral error, the current lateral error change rate, the current heading angle error and the current heading angle error change rate of the target vehicle; a second acquisition module, configured to acquire an objective function; wherein the objective function is constructed based on a target dynamics model and a target tire model; the target dynamics model is a two-degree-of-freedom dynamics model of the target vehicle under a tire blowout condition, and the target tire model is a tire model of the target vehicle under the tire blowout condition; a determination module, configured to determine a target steering wheel angle and a target longitudinal acceleration of the target vehicle based on the current lateral error, the current lateral error change rate, the current heading angle error, the current heading angle error change rate, and the objective function, so as to safely control the target vehicle in the tire blowout condition based on the target steering wheel angle and the target longitudinal acceleration.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the vehicle safety control method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the vehicle safety control method according to any one of claims 1 to 7 is implemented.

Images