Vehicle control method, control device, electronic device, vehicle and storage medium

Abstract

The invention provides a vehicle control method and device, an electronic device, a vehicle and a storage medium, and relates to the field of automobile control, and the method comprises the steps: determining a rear wheel expected turning angle value of the vehicle according to the obtained current yaw velocity, lateral acceleration and longitudinal velocity of the vehicle; and controlling the rear wheel to rotate according to the rear wheel expected corner value. According to the vehicle control method provided by the invention, the control of the rear wheels is only determined by the yaw angle and the centroid sideslip angle of the vehicle in the current state. According to the method, the yaw angle and the side slip angle of the vehicle are taken as control quantities, the traditional self-adaptive LQR control theory is improved, and the rear wheel steering angle value with higher precision is calculated in real time, so that the accuracy and the reliability of vehicle steering control can be effectively improved, the stability and the safety of the vehicle are better, and the driving and riding requirements of the vehicle are well met.

Description

Technical Field

[0001] The present invention relates to the field of automobile control technology, and in particular to a vehicle control method, a control device, an electronic device, a vehicle and a readable storage medium. Background Art

[0002] At present, lateral motion control is the core of the entire motion control system in automobile steering control. The accuracy of lateral motion control will not only affect the tracking accuracy of the automobile to the target path, but also affect the stability and comfort of the entire vehicle.

[0003] The best lateral motion control method currently used is the linear quadratic optimal control (LQR) theory. However, there is no independent control method for the rear wheels in this theory. The front wheels and related information must be involved to obtain the rear wheel steering angle value, resulting in inaccurate rear wheel steering angle values, poor accuracy and reliability of vehicle steering control, low vehicle stability and safety, and failure to meet vehicle driving needs. Summary of the invention

[0004] In view of the above problems, the present invention proposes a vehicle control method, a control device, an electronic device, a vehicle and a readable storage medium.

[0005] An embodiment of the present invention provides a vehicle control method, the vehicle control method comprising:

[0006] Determine the expected rear wheel turning angle value of the vehicle according to the acquired current yaw angular velocity, lateral acceleration and longitudinal velocity of the vehicle;

[0007] The rear wheel rotation is controlled according to the desired rear wheel turning angle value.

[0008] Optionally, determining the expected rear wheel turning angle value of the vehicle according to the acquired current yaw angular velocity, lateral acceleration and longitudinal velocity of the vehicle includes:

[0009] Determining a current sideslip angle of the vehicle according to the yaw rate, the lateral acceleration and the longitudinal velocity;

[0010] The expected rear wheel turning angle value is determined according to the center of mass sideslip angle and the yaw angular velocity.

[0011] Optionally, determining a current center of mass sideslip angle of the vehicle according to the yaw angular velocity, the lateral acceleration, and the longitudinal velocity includes:

[0012] Acquiring the yaw angular velocity, the lateral acceleration and the current speed of the vehicle;

[0013] The center-of-mass sideslip angle is obtained by performing calculation based on the yaw angular velocity, the lateral acceleration, and the longitudinal velocity in the vehicle speed.

[0014] Optionally, the magnitude of the center of mass sideslip angle is determined by the magnitude of the yaw angular velocity, the magnitude of the lateral acceleration and the magnitude of the longitudinal velocity.

[0015] Optionally, when the magnitude of the lateral acceleration and the magnitude of the longitudinal velocity remain constant, the greater the yaw angular velocity, the smaller the center of mass sideslip angle;

[0016] When the magnitude of the yaw angular velocity and the magnitude of the longitudinal velocity remain constant, the greater the lateral acceleration, the greater the center of mass sideslip angle;

[0017] When the magnitude of the lateral acceleration and the magnitude of the yaw angular velocity remain constant, the greater the longitudinal velocity, the smaller the center of mass sideslip angle.

[0018] Optionally, performing calculation based on the yaw angular velocity, the lateral acceleration and the longitudinal velocity in the vehicle speed to obtain the center of mass sideslip angle includes:

[0019] Based on the yaw rate, the lateral acceleration and the longitudinal speed in the vehicle speed, a preset formula is used to calculate to obtain the center of mass sideslip angle;

[0020] The expression of the preset formula is as follows:

[0021]

[0022] In the above formula, β represents the center of mass side slip angle, a y represents the lateral acceleration, h represents the longitudinal velocity, w r represents the yaw angular velocity.

[0023] Optionally, determining the expected rear wheel turning angle value according to the center of mass sideslip angle and the yaw angular velocity includes:

[0024] The expected rear wheel steering angle value is obtained by performing calculations based on the center of mass sideslip angle and the yaw angular velocity in combination with a preset cost function, a preset Riccati equation and a preset two-degree-of-freedom steering model.

[0025] Optionally, the expected rear wheel steering angle value is obtained by performing calculations based on the sideslip angle of the center of mass and the yaw angular velocity in combination with a preset cost function, a preset Riccati equation and a preset two-degree-of-freedom steering model, including:

[0026] The center of mass sideslip angle and the yaw angular velocity are used as inputs of a preset cost function, and the smaller the value of the preset cost function is, the smaller the yaw angle and the center of mass sideslip angle of the vehicle are during the steering process;

[0027] Adjusting the weight parameters in the preset cost function according to the vehicle condition;

[0028] Based on the adjusted weight parameters, the preset Riccati equation and the preset two-degree-of-freedom steering model are combined to perform calculations to obtain the optimal weight matrix;

[0029] According to the optimal weight matrix, the state feedback is substituted into the preset cost function for calculation to obtain the expected rear wheel steering angle value.

[0030] Optionally, the weight parameters include: a first weight parameter and a second weight parameter;

[0031] Adjusting the weight parameters in the preset cost function according to the vehicle condition includes:

[0032] Part of the first weight parameters and part of the second weight parameters are adjusted according to the current vehicle speed in the vehicle condition, and the remaining parameters of the two weight parameters are fixed values.

[0033] Optionally, the first weight parameter The second weight parameter Among them, q 12 ,q 21 , r 12 , r 21 is a fixed value; q 11 ,q 22 , r 11 , r 22 The parameters adjusted according to the current vehicle speed include:

[0034] q 11 =p1+λ1v

[0035] q 22 =p2+λ2v

[0036] r 11 =p3+λ3v

[0037] r 22 =p4+λ4v

[0038] In the above four equations, p1, p2, p3, and p4 are all proportional constants, λ1, λ2, λ3, and λ4 are all adaptive factors, and v is the current vehicle speed.

[0039] Optionally, based on the adjusted weight parameters, a preset Riccati equation and a preset two-degree-of-freedom steering model are combined to perform calculations to obtain an optimal weight matrix, including:

[0040] Based on the adjusted weight parameters, updating the system matrix extracted from the preset two-degree-of-freedom steering model;

[0041] Substituting the updated system matrix, the input matrix and the adjusted weight parameter into the preset Riccati equation for calculation to obtain a solution of the preset Riccati equation, wherein the input matrix is ​​extracted from the preset two-degree-of-freedom steering model;

[0042] The optimal weight matrix is ​​obtained by calculation according to the solution of the preset Riccati equation.

[0043] Optionally, according to the optimal weight matrix, state feedback is substituted into the preset cost function for calculation to obtain the expected rear wheel steering angle value, including:

[0044] The optimal weight matrix Substitute the state feedback u=-Kx into the preset cost function for calculation to obtain the rear wheel expected turning angle value δ r The operation formula is:

[0045] δ r =-(k 21 β+k 22 w r )

[0046] In the above formula, β represents the sideslip angle of the center of mass, w r represents the yaw angular velocity;

[0047] The x represents the input of the cost function, namely: the sideslip angle of the center of mass and the yaw rate;

[0048] The value of u is determined by the optimal weight matrix and the current vehicle state, and the current vehicle state includes: the yaw rate and the executed sideslip angle of the current vehicle.

[0049] Optionally, when the current vehicle speed is low, the weight of the center of mass sideslip angle in the calculation of the expected rear wheel turning angle value is greater than the weight of the yaw angular velocity;

[0050] When the current vehicle speed is high, the weight of the yaw rate in the calculation of the expected rear wheel turning angle value is greater than the weight of the center of mass sideslip angle.

[0051] Optionally, controlling the rotation of the rear wheels according to the expected rear wheel turning angle value includes:

[0052] Converting the expected rear wheel turning angle value to obtain the rear wheel lead screw displacement;

[0053] Based on the displacement of the rear wheel screw, the rotation of the rear wheel is controlled by controlling the movement of the transmission mechanism.

[0054] An embodiment of the present invention provides a vehicle control device, the vehicle control device comprising:

[0055] A rear wheel desired steering angle value determination module is used to determine the vehicle's rear wheel desired steering angle value according to the acquired vehicle's current yaw angular velocity, lateral acceleration and longitudinal velocity;

[0056] The rear wheel rotation control module is used to control the rear wheel rotation according to the rear wheel expected rotation angle value.

[0057] An embodiment of the present invention provides an electronic device, which includes a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program so that the electronic device executes any of the vehicle control methods described above.

[0058] An embodiment of the present invention provides a vehicle, wherein the vehicle includes the vehicle control device as described above or the electronic device as described above.

[0059] An embodiment of the present invention provides a readable storage medium having a program stored thereon, and when the program is executed by a processor, the steps in any of the above-mentioned vehicle control methods are implemented.

[0060] The vehicle control method provided by the present invention first determines the expected rear wheel turning angle value of the vehicle according to the acquired current yaw angular velocity, lateral acceleration and longitudinal speed of the vehicle; and finally controls the rotation of the rear wheels according to the expected rear wheel turning angle value.

[0061] The present invention aims at the problem that the linear quadratic optimal control theory used in the traditional lateral motion control method has no independent control method for the rear wheels, and the rear wheel steering angle value can only be obtained by involving the front wheels and related information. A new vehicle control method that is independent of the front wheels and related information and has no signal connection with the front wheels is creatively proposed.

[0062] In the vehicle control method proposed by the present invention, the control of the rear wheels is determined only by the yaw angle and the sideslip angle of the center of mass of the vehicle in the current state. The yaw angle and the sideslip angle of the center of mass of the vehicle are used as the control quantities, the traditional adaptive LQR control theory is improved, and the rear wheel steering angle value with higher accuracy is calculated in real time, thereby effectively improving the accuracy and reliability of the vehicle steering control, making the vehicle more stable and safer, and meeting the driving and riding requirements of the vehicle well, and having high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0064] Figure 1 A flow chart of a vehicle control method provided by an embodiment of the present invention;

[0065] Figure 2 An exemplary steering system diagram provided for an embodiment of the present invention;

[0066] Figure 3 Corresponding to an embodiment of the present invention Figure 2 A flowchart of rear wheel steering;

[0067] Figure 4 A block diagram of an LQR yaw control system provided by an embodiment of the present invention;

[0068] Figure 5 A block diagram of a vehicle control device provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0069] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, are only part of the embodiments of the present invention, not all of the embodiments, and are not used to limit the present invention.

[0070] The inventors have discovered that the rear wheel steering angle value obtained by calculating the linear quadratic optimal control theory used in the current lateral motion control method is not accurate enough.

[0071] The inventor further studied and found that the reason for the above problem is that there is no independent control method for the rear wheels in the current theory, and the front wheels and related information must be involved to obtain the rear wheel angle value. For example, in the lateral control of some vehicles, the front wheel output is adjusted in combination with the expected trajectory to drive the rear wheels to track the trajectory; in the lateral control of some vehicles, the rear wheels are mainly controlled by establishing a proportional relationship between the front wheels and the rear wheels, and the prerequisite for the implementation of this type of control method is: it is necessary to assume that the vehicle steering is a uniform circular motion, and a single-input single-output model is established based on this. On the basis of this model, the rear wheel control is achieved by combining the proportional relationship between the front wheels and the rear wheels; and more traditional rear wheel steering lateral control is used, which uses the current vehicle speed, steering wheel angle, steering wheel speed and front wheel angle value as input, and controls the rotation of the rear wheels according to the logic of artificial experience.

[0072] In the above control methods, the front wheels and their related information are used, and the rear wheel steering angle value can only be obtained indirectly, which will naturally lead to the obtained rear wheel steering angle value being inaccurate. If the rear wheel steering angle value is not accurate enough, the accuracy and reliability of the vehicle steering control will naturally deteriorate, making the vehicle's stability and safety low and unable to meet the vehicle's driving needs well.

[0073] In view of the above problems, after extensive research and testing, the present invention creatively proposes a vehicle control method, a control device, an electronic device, a vehicle and a readable storage medium of the present invention. The technical solution proposed by the present invention is explained and illustrated in detail below.

[0074] The vehicle control method of the present invention refers to Figure 1 The flowchart shown includes:

[0075] Step 101: Determine the expected rear wheel turning angle value of the vehicle according to the acquired current yaw angular velocity, lateral acceleration and longitudinal velocity of the vehicle.

[0076] First, you need to obtain the current yaw rate, lateral acceleration and longitudinal speed of the vehicle, that is, obtain the real-time values ​​of the yaw rate, lateral acceleration and longitudinal speed. There are many ways to obtain them, such as: through sensors, through ARS (Active Wheel Steering), through EPS (Electric Power Steering), etc.

[0077] A preferred method for determining the expected turning angle value of the rear wheels of a vehicle includes:

[0078] First, the current sideslip angle of the vehicle's center of mass is determined based on the yaw rate, lateral acceleration, and longitudinal speed; then, the desired rear wheel turning angle is determined based on the sideslip angle and yaw rate.

[0079] After obtaining the real-time values ​​of the yaw rate, lateral acceleration and longitudinal speed, the current sideslip angle of the vehicle's center of mass can be determined based on the real-time values ​​of these quantities.

[0080] A better method for determining the current center of mass slip angle of a vehicle includes: obtaining the current speed of the vehicle in addition to the yaw rate and lateral acceleration; calculating the center of mass slip angle using a preset formula based on the real-time values ​​of the yaw rate, lateral acceleration, and longitudinal speed in the vehicle speed. It can be seen that the size of the center of mass slip angle is jointly determined by the size of the yaw rate, the size of the lateral acceleration, and the size of the longitudinal speed.

[0081] When the magnitude of the lateral acceleration and the longitudinal velocity remain unchanged, the greater the yaw angular velocity, the smaller the center of mass sideslip angle; when the magnitude of the yaw angular velocity and the longitudinal velocity remain unchanged, the greater the lateral acceleration, the greater the center of mass sideslip angle; when the magnitude of the lateral acceleration and the yaw angular velocity remain unchanged, the greater the longitudinal velocity, the smaller the center of mass sideslip angle.

[0082] Based on the yaw rate, lateral acceleration and longitudinal velocity in the vehicle speed, the center of mass sideslip angle can be calculated using a preset formula. The expression of the preset formula is as follows:

[0083]

[0084] In the above formula, β represents the sideslip angle of the center of mass, a y represents lateral acceleration, h represents longitudinal velocity, and w r Represents the yaw rate. The preset formula can be used to obtain the sideslip angle of the center of mass quickly and simply.

[0085] After obtaining the center of mass sideslip angle, the expected rear wheel steering angle value of the vehicle is determined according to the center of mass sideslip angle and the yaw rate. A preferred method for determining the expected rear wheel steering angle value includes:

[0086] According to the sideslip angle and yaw rate of the center of mass, the expected steering angle of the rear wheel is obtained by combining the preset cost function, the preset Riccati equation and the preset two-degree-of-freedom steering model. The specific steps include:

[0087] Step S1: using the center of mass sideslip angle and the yaw rate as inputs of a preset cost function. The smaller the value of the preset cost function is, the smaller the yaw angle and the center of mass sideslip angle of the vehicle are during the steering process.

[0088] The preset cost function is constructed in advance, and its goal is to minimize the value of the preset cost function. The smaller the value is, the smaller the yaw angle and sideslip angle of the corresponding vehicle during the steering process. The smaller the yaw angle and sideslip angle of the center of mass of the vehicle during the steering process, the better the stability and safety of the vehicle. On this basis, the expected rear wheel turning angle value obtained is more accurate, and the accuracy and reliability of the natural steering control are better.

[0089] A better preset cost function J can be set as follows:

[0090]

[0091] In the preset cost function, x represents the input quantity, that is, the sideslip angle of the center of mass and the yaw angular velocity, T represents the transpose of the matrix, Q and R are two weight parameters, and the meaning of u is given below and will not be repeated here.

[0092] The preset cost function proposed in the present invention is different from the traditional cost function. It is set to minimize the yaw angle and the sideslip angle of the center of mass of the vehicle during the steering process in order to obtain the precise expected steering angle value of the rear wheel. Its input is no longer related to the front wheel or related information of the front wheel, and is no longer limited by any information of the front wheel. Instead, it directly controls the rear wheel accurately, improving the accuracy of the expected steering angle value of the rear wheel.

[0093] Step S2: adjusting the weight parameters in the preset cost function according to the vehicle condition.

[0094] After the preset cost function is set, the weight parameters need to be set or adjusted. Preferably, the weight parameters include: a first weight parameter Q and a second weight parameter R; some parameters in the first weight parameter Q and some parameters in the second weight parameter R are adjusted according to the current vehicle speed in the vehicle condition, and the remaining parameters in the two weight parameters are fixed values. This reduces the amount of calculation and adjustment while ensuring the accuracy of the weight parameters. Specifically:

[0095] The first weight parameter The second weight parameter Among them, q 12 ,q 21 , r 12 , r 21 is a fixed value; q 11 ,q 22 , r 11 , r 22 The parameters adjusted according to the current vehicle speed, that is, the parameters adjusted according to the real-time value of the vehicle speed, include:

[0096] q 11 =p1+λ1v

[0097] q 22 =p2+λ2v

[0098] r 11 =p3+λ3v

[0099] r 22 =p4+λ4v

[0100] In the above four equations, p1, p2, p3, and p4 are all proportional constants, λ1, λ2, λ3, and λ4 are all adaptive factors, and v is the current vehicle speed.

[0101] Step S3: Based on the adjusted weight parameters, a calculation is performed in combination with a preset Riccati equation and a preset two-degree-of-freedom steering model to obtain an optimal weight matrix.

[0102] After the weight parameters are adjusted according to the real-time value of the vehicle speed, the optimal weight matrix is ​​obtained based on the adjusted weight parameters, combined with the preset Ricaati equation and the preset two-degree-of-freedom steering model. The optimal weight matrix is ​​needed because the value of the preset cost function is minimized, and the state feedback idea needs to be used. The specific description is shown below and will not be repeated here.

[0103] A better method to obtain the optimal weight matrix includes:

[0104] First, it is necessary to build the preset Riccati equation and the preset two-degree-of-freedom steering model in advance, and then establish the equation based on the kinematics and dynamics of the two-degree-of-freedom steering model. The so-called two-degree-of-freedom steering model is generally obtained by simplifying the four-wheel steering vehicle model, which can accurately reflect the kinematics and dynamics of the four-wheel steering vehicle during the steering process.

[0105] For example, a better equation based on the kinematics and dynamics of the two-degree-of-freedom steering model can be expressed as follows:

[0106]

[0107] After obtaining the above equations, the kinematic and dynamic equations are simplified to obtain the differential equations expressed as follows:

[0108]

[0109] Then, according to the above differential equation, the state space expression is established as follows:

[0110]

[0111] In the above three equations, F y1 and F y2 Represents the lateral force of the front and rear wheels respectively; F x1 and F x2Represent the longitudinal forces of the front and rear wheels respectively; a and b represent the distances from the center of mass to the front and rear axles respectively, and the sum of the two is the wheelbase L; δ1 and δ2 represent the front and rear wheel turning angles respectively; α1 and α2 represent the side slip angles respectively; a x and a y Represent the longitudinal acceleration and lateral acceleration of the vehicle respectively; V1 and V2 represent the speed at the center of the front and rear wheels respectively; I z represents the moment of inertia of the vehicle around the vertical direction; m represents the mass of the vehicle; k1 and k2 represent the cornering stiffness of the front and rear wheels respectively. The u here is the u in the above cost function.

[0112] After obtaining the state space expression, the system matrix and input matrix can be extracted based on the state space expression. The system matrix A and input matrix B are expressed as follows:

[0113]

[0114]

[0115] After extracting the matrix, the system matrix and the input matrix can be preset in the processor as preprocessing items. After that, when the weight parameters are adjusted, it is only necessary to update the system matrix extracted from the preset two-degree-of-freedom steering model based on the adjusted weight parameters.

[0116] After updating the system matrix, the updated system matrix, the preset input matrix obtained and extracted, and the adjusted weight parameters (i.e., the adjusted Q, R) are substituted into the preset Riccati equation for calculation to obtain the solution of the preset Riccati equation. The preset Riccati equation is: T P+PA-PBR -1 B T P+Q=0. Since A, B, Q, and R can all be calculated, the solution P of the preset Riccati equation can be calculated.

[0117] Get the solution P of the preset Riccati equation, and substitute the solution P of the preset Riccati equation into the equation corresponding to the optimal weight matrix: K = R -1 B T P, the optimal weight matrix can be obtained by calculation.

[0118] Step S4: According to the optimal weight matrix, the state feedback is substituted into the cost function for calculation to obtain the expected steering angle value of the rear wheel.

[0119] Get the optimal weight matrix Then, the optimal weight matrix By using the state feedback u = -Kx (i.e. the state feedback idea can minimize the value obtained by the preset cost function), substituting it into the preset cost function for calculation, the expected rear wheel turning angle value δ can be obtained. r The operation formula is:

[0120] δ r =-(k 21 β+k 22 w r )

[0121] In the above formula, β represents the center of mass sideslip angle calculated according to the preset formula, w r represents the real-time value of the yaw rate obtained; x is the input of the cost function, and the value of u is the same as mentioned above, which is determined by the optimal weight matrix and the current vehicle state. The current vehicle state includes: the yaw rate of the current vehicle and the execution sideslip angle.

[0122] The accurate rear wheel expected turning angle value δ can be obtained by calculating the above formula r From the above analysis, it can be seen that when the current vehicle speed is low, the weight of the center of mass slip angle in the calculation of the expected rear wheel turning angle value is greater than the weight of the yaw angular velocity; when the current vehicle speed is high, the weight of the yaw angular velocity in the calculation of the expected rear wheel turning angle value is greater than the weight of the center of mass slip angle.

[0123] It should be noted that the process of the above steps S1 to S4 finally obtains the desired rear wheel turning angle value δ r In actual use, since the system matrix, input matrix, preset cost function, preset Ricatti equation, etc. can be set in advance, the system matrix, input matrix (or two-degree-of-freedom steering model), preset cost function, preset Ricatti equation, and the calculated rear wheel expected steering angle value δ can be used. r The formula is directly preset in the relevant equipment, such as in the controller. In this way, after obtaining the current yaw rate, lateral acceleration, and vehicle speed of the vehicle, the center of mass slip angle can be calculated according to the preset formula, and the model is updated according to the vehicle speed (that is, the system matrix A extracted from the two-degree-of-freedom steering model is updated) and the weight parameters Q and R are calculated based on the center of mass slip angle and yaw rate. r The formula is used to directly calculate the expected rear wheel turning angle δ r .

[0124] In addition, it can be seen from the above description that the present invention proposes a multi-input multi-output model that can simultaneously control the two states of yaw angular velocity and center of mass sideslip angle, and there is no need to assume that the steering of the vehicle is a uniform circular motion. The accuracy of the entire model is better than that of the model in the traditional way, and the accuracy of the expected steering angle value of the rear wheel is further improved.

[0125] Step 102: Control the rotation of the rear wheels according to the desired rear wheel turning angle value.

[0126] After the desired rear wheel turning angle value is calculated, the rear wheel rotation is finally controlled according to the desired rear wheel turning angle value. A preferred method includes: firstly converting the calculated desired rear wheel turning angle value to obtain the displacement of the rear wheel screw; then based on the displacement of the rear wheel screw, controlling the movement of the transmission mechanism to control the rotation of the rear wheel.

[0127] Take self-driving cars as an example. Figure 2 An exemplary steering system diagram is shown: Under normal circumstances, when a vehicle is driving along a certain driving trajectory, it will first receive the desired trajectory sent by the navigation system, and output the steering wheel angle through the current position and the desired trajectory to make the steering wheel turn. The steering wheel rotation is transmitted to the REPS (Rack-drive Electric Power Steering system, which includes the rear wheel steering controller) through the steering column to drive the front wheels to turn.

[0128] As the front wheels turn, the vehicle body begins to turn. At this time, the vehicle data such as the yaw angle, yaw rate, and lateral acceleration can be obtained through sensors and other means. After obtaining these data, the rear wheel steering controller will calculate the expected rear wheel steering angle value according to the control method proposed in the present invention and send it to the left and right rear wheel controller assemblies. Figure 3 The rear wheel steering controller sends the calculated desired rear wheel steering angle value to the left and right rear wheel controller assemblies. After receiving the desired rear wheel steering angle value, the left and right rear wheel controller assemblies obtain the displacement of the rear wheel lead screw by conversion, and control the movement of the belt transmission mechanism to pull the lead screw, and finally control the rotation of the left and right rear wheels.

[0129] The vehicle control method of the present invention can be used Figure 4 The block diagram of the LQR yaw control system shown is summarized as follows: the driver model (a model that can calculate the desired front wheel turning angle in a conventional manner) calculates based on the current position and the desired trajectory to obtain the desired front wheel turning angle to the controlled object (i.e., the front wheel). When the state of the controlled object's front wheel changes, the corresponding vehicle state is also changed, and the vehicle speed, yaw angular velocity, lateral acceleration and other data will all change.

[0130] The yaw rate, lateral acceleration and longitudinal speed are calculated using the preset formula 1 (i.e. the formula for calculating the center of mass sideslip angle) to obtain the center of mass sideslip angle. At the same time, the model is updated according to the vehicle speed (i.e. the system matrix A extracted from the two-degree-of-freedom steering model is updated) and the weight parameters (i.e. the weight parameters Q and R) are updated. The preset formula 2 (i.e. the formula for calculating the expected rear wheel turning angle value) is used. In combination with the updated model and the updated weight parameters, the center of mass sideslip angle and yaw rate are calculated to obtain the expected rear wheel turning angle (i.e. the expected rear wheel turning angle value) and sent to the controlled object (i.e. the rear wheel), so that the rear wheel rotates according to the expected rear wheel turning angle value, thereby achieving the goal of accurately controlling the rear wheel.

[0131] From the above explanations and descriptions, it can be seen that in the vehicle control method proposed by the present invention, the control of the rear wheels is only determined by the yaw angle and the sideslip angle of the center of mass of the vehicle in the current state. The yaw angle and the sideslip angle of the center of mass of the vehicle are used as the control quantities, and the traditional adaptive LQR control theory is improved to obtain the accurate rear wheel steering angle value by real-time calculation. Since the rear wheel steering angle value has a higher accuracy, it can effectively improve the accuracy and reliability of the vehicle steering control, thereby making the vehicle more stable and safe, and well meeting the vehicle driving and riding requirements.

[0132] Based on the above vehicle control method, the present invention also proposes a vehicle control device, the block diagram of which is as follows: Figure 5 As shown, it includes:

[0133] The rear wheel desired steering angle value determination module 510 is used to determine the rear wheel desired steering angle value of the vehicle according to the acquired current yaw angular velocity, lateral acceleration and longitudinal velocity of the vehicle;

[0134] The rear wheel rotation control module 520 is used to control the rear wheel rotation according to the rear wheel expected rotation angle value.

[0135] Optionally, the rear wheel expected turning angle value determination module 510 includes:

[0136] A center of mass sideslip angle determination submodule, used to determine a current center of mass sideslip angle of the vehicle according to the yaw angular velocity, the lateral acceleration and the longitudinal velocity;

[0137] The rear wheel desired steering angle value determination submodule is used to determine the rear wheel desired steering angle value according to the center of mass sideslip angle and the yaw angular velocity.

[0138] Optionally, the center of mass sideslip angle determination submodule is specifically used for:

[0139] Acquiring the yaw angular velocity, the lateral acceleration and the current speed of the vehicle;

[0140] Based on the yaw rate, the lateral acceleration and the longitudinal speed in the vehicle speed, a preset formula is used to calculate to obtain the center of mass sideslip angle;

[0141] The magnitude of the center of mass sideslip angle is determined by the magnitude of the yaw angular velocity, the magnitude of the lateral acceleration and the magnitude of the longitudinal velocity;

[0142] When the magnitude of the lateral acceleration and the magnitude of the longitudinal velocity remain constant, the greater the yaw angular velocity, the smaller the center of mass sideslip angle;

[0143] When the magnitude of the yaw angular velocity and the magnitude of the longitudinal velocity remain constant, the greater the lateral acceleration, the greater the center of mass sideslip angle;

[0144] When the magnitude of the lateral acceleration and the magnitude of the yaw angular velocity remain constant, the greater the longitudinal velocity, the smaller the center of mass sideslip angle;

[0145] The expression of the preset formula used in the mass center sideslip angle determination submodule is as follows:

[0146]

[0147] In the above formula, β represents the center of mass side slip angle, a y represents the lateral acceleration, h represents the longitudinal velocity, w r represents the yaw angular velocity.

[0148] Optionally, the rear wheel expected turning angle value determination submodule is specifically used for:

[0149] The expected rear wheel steering angle value is obtained by performing calculations based on the center of mass sideslip angle and the yaw angular velocity in combination with a preset cost function, a preset Riccati equation and a preset two-degree-of-freedom steering model.

[0150] The rear wheel expected turning angle value determination submodule comprises:

[0151] A function input module, used for taking the center of mass sideslip angle and the yaw angular velocity as input quantities of the preset cost function, wherein the smaller the value obtained by the preset cost function is, the smaller the yaw angle and the center of mass sideslip angle of the vehicle are during the steering process;

[0152] An adjustment parameter submodule, used to adjust the weight parameters in the preset cost function according to the vehicle condition;

[0153] A weight matrix calculation submodule is used to calculate based on the adjusted weight parameters in combination with a preset Riccati equation and a preset two-degree-of-freedom steering model to obtain an optimal weight matrix;

[0154] A turning angle calculation submodule is used to calculate the expected turning angle value of the rear wheel by substituting the state feedback into the preset cost function according to the optimal weight matrix;

[0155] Wherein, the weight parameters include: a first weight parameter and a second weight parameter;

[0156] The adjustment parameter submodule is specifically used for:

[0157] According to the current vehicle speed in the vehicle condition, some parameters in the first weight parameter and some parameters in the second weight parameter are adjusted, and the remaining parameters in the two weight parameters are fixed values;

[0158] The first weight parameter The second weight parameter Among them, q 12 ,q 21 , r 12 , r 21 is a fixed value; q 11 ,q 22 , r 11 , r 22 The parameters adjusted according to the current vehicle speed include:

[0159] q 11 =p1+λ1v

[0160] q 22 =p2+λ2v

[0161] r 11 =p3+λ3v

[0162] r 22 =p4+λ4v

[0163] In the above four equations, p1, p2, p3, and p4 are all proportional constants, λ1, λ2, λ3, and λ4 are all adaptive factors, and v is the current vehicle speed.

[0164] Optionally, the weight matrix operation submodule includes:

[0165] An updating parameter unit, used for updating a system matrix extracted from the preset two-degree-of-freedom steering model;

[0166] Substituting into a solving unit, for substituting the updated system matrix, the input matrix and the adjusted weight parameter into the preset Riccati equation for calculation to obtain a solution of the preset Riccati equation, wherein the input matrix is ​​extracted from the preset two-degree-of-freedom steering model;

[0167] A calculation unit is used to calculate and obtain the optimal weight matrix according to the solution of the preset Riccati equation.

[0168] Optionally, the substitution solving unit is specifically used for:

[0169] The optimal weight matrix Substitute the state feedback u=-Kx into the preset cost function for calculation to obtain the rear wheel expected turning angle value δ r The operation formula is:

[0170] δ r =-(k 21 β+k 22 w r )

[0171] In the above formula, β represents the sideslip angle of the center of mass, w r represents the yaw angular velocity;

[0172] The x represents the input of the cost function, namely: the sideslip angle of the center of mass and the yaw rate;

[0173] The value of u is determined by the optimal weight matrix and the current vehicle state, wherein the current vehicle state includes: the yaw rate and the executed sideslip angle of the current vehicle;

[0174] When the current vehicle speed is low, the weight of the center of mass sideslip angle in the calculation of the expected rear wheel turning angle value is greater than the weight of the yaw angular velocity;

[0175] When the current vehicle speed is high, the weight of the yaw rate in the calculation of the expected rear wheel turning angle value is greater than the weight of the center of mass sideslip angle.

[0176] Optionally, the rear wheel rotation control module 520 is specifically used for:

[0177] Converting the expected rear wheel turning angle value to obtain the rear wheel lead screw displacement;

[0178] Based on the displacement of the rear wheel screw, the rotation of the rear wheel is controlled by controlling the movement of the transmission mechanism.

[0179] Based on the above vehicle control method, the present invention also proposes an electronic device, which includes a processor and a memory, the memory stores a computer program, and the processor executes the computer program so that the electronic device executes the vehicle control method as described in any one of steps 101 to 102.

[0180] Based on the above vehicle control method, the present invention further proposes a vehicle, which includes the above vehicle control device or the above electronic device.

[0181] Based on the above vehicle control method, the present invention further proposes a readable storage medium on which a program is stored. When the program is executed by a processor, the vehicle control method described in any one of steps 101 to 102 is implemented.

[0182] In summary, the vehicle control method provided by the present invention first determines the desired rear wheel steering angle value of the vehicle based on the acquired current yaw angular velocity, lateral acceleration and longitudinal speed of the vehicle; and finally controls the rotation of the rear wheels based on the desired rear wheel steering angle value.

[0183] The present invention aims at the problem that the linear quadratic optimal control theory used in the traditional lateral motion control method has no independent control method for the rear wheels, and the rear wheel steering angle value can only be obtained by involving the front wheels and related information. A new vehicle control method that is independent of the front wheels and related information and has no signal connection with the front wheels is creatively proposed.

[0184] In the vehicle control method proposed in the present invention, the control of the rear wheels is determined only by the yaw angle and the sideslip angle of the center of mass of the vehicle in the current state. The yaw angle and the sideslip angle of the center of mass of the vehicle are used as the control quantities, the traditional adaptive LQR control theory is improved, and the accurate rear wheel steering angle value is calculated in real time. A multi-input multi-output model that can simultaneously control the two states of yaw angular velocity and the sideslip angle of the center of mass is proposed, and there is no need to assume that the steering of the vehicle is a uniform circular motion. The model accuracy is better than the model under the traditional method, and the accuracy of the rear wheel steering angle value is further improved. During the driving process of the vehicle, at low speed, the change of the sideslip angle of the center of mass is emphasized, and at high speed, rollover is prevented and the weight of the yaw angle is increased. Since the accuracy of the rear wheel steering angle value is higher, the accuracy and reliability of the vehicle steering control can be effectively improved, thereby improving the stability and safety of the vehicle, meeting the driving and riding requirements of the vehicle well, and having high practicality.

[0185] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0186] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0187] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A vehicle control method, characterized in that: The vehicle control method comprises: Determine the expected rear wheel turning angle value of the vehicle according to the acquired current yaw angular velocity, lateral acceleration and longitudinal velocity of the vehicle; The rear wheel rotation is controlled according to the desired rear wheel turning angle value.

2. The vehicle control method according to claim 1, characterized in that: According to the obtained current yaw rate, lateral acceleration and longitudinal speed of the vehicle, the expected rear wheel steering angle value of the vehicle is determined, including: Determining a current sideslip angle of the vehicle according to the yaw rate, the lateral acceleration and the longitudinal velocity; The expected rear wheel turning angle value is determined according to the center of mass sideslip angle and the yaw angular velocity.

3. The vehicle control method according to claim 2, characterized in that: Determining a current center-of-mass sideslip angle of the vehicle according to the yaw angular velocity, the lateral acceleration, and the longitudinal velocity includes: Acquiring the yaw angular velocity, the lateral acceleration and the current speed of the vehicle; The center-of-mass sideslip angle is obtained by performing calculation based on the yaw angular velocity, the lateral acceleration, and the longitudinal velocity in the vehicle speed.

4. The vehicle control method according to claim 2, characterized in that: The magnitude of the center of mass sideslip angle is determined by the magnitude of the yaw angular velocity, the magnitude of the lateral acceleration and the magnitude of the longitudinal velocity.

5. The vehicle control method according to claim 4, characterized in that: When the magnitude of the lateral acceleration and the magnitude of the longitudinal velocity remain constant, the greater the yaw angular velocity, the smaller the center of mass sideslip angle; When the magnitude of the yaw angular velocity and the magnitude of the longitudinal velocity remain constant, the greater the lateral acceleration, the greater the center of mass sideslip angle; When the magnitude of the lateral acceleration and the magnitude of the yaw angular velocity remain constant, the greater the longitudinal velocity, the smaller the center of mass sideslip angle.

6. The vehicle control method according to claim 3, characterized in that: The method of calculating the center of mass sideslip angle based on the yaw rate, the lateral acceleration and the longitudinal speed in the vehicle speed includes: Based on the yaw rate, the lateral acceleration and the longitudinal speed in the vehicle speed, a preset formula is used to calculate to obtain the center of mass sideslip angle; The expression of the preset formula is as follows: In the above formula, β represents the center of mass side slip angle, a y represents the lateral acceleration, h represents the longitudinal velocity, w r represents the yaw angular velocity.

7. The vehicle control method according to claim 2, characterized in that: Determining the expected rear wheel turning angle value according to the center of mass sideslip angle and the yaw angular velocity includes: The expected rear wheel steering angle value is obtained by performing calculations based on the center of mass sideslip angle and the yaw angular velocity in combination with a preset cost function, a preset Riccati equation and a preset two-degree-of-freedom steering model.

8. The vehicle control method according to claim 7, characterized in that: According to the sideslip angle of the center of mass and the yaw rate, a preset cost function, a preset Riccati equation and a preset two-degree-of-freedom steering model are combined to calculate and obtain the expected steering angle value of the rear wheel, including: The center of mass sideslip angle and the yaw angular velocity are used as inputs of a preset cost function, and the smaller the value of the preset cost function is, the smaller the yaw angle and the center of mass sideslip angle of the vehicle are during the steering process; Adjusting the weight parameters in the preset cost function according to the vehicle condition; Based on the adjusted weight parameters, the preset Riccati equation and the preset two-degree-of-freedom steering model are combined to perform calculations to obtain the optimal weight matrix; According to the optimal weight matrix, the state feedback is substituted into the preset cost function for calculation to obtain the expected rear wheel steering angle value.

9. The vehicle control method according to claim 8, characterized in that: The weight parameters include: a first weight parameter and a second weight parameter; Adjusting the weight parameters in the preset cost function according to the vehicle condition includes: Part of the first weight parameters and part of the second weight parameters are adjusted according to the current vehicle speed in the vehicle condition, and the remaining parameters of the two weight parameters are fixed values.

10. The vehicle control method according to claim 9, characterized in that: The first weight parameter The second weight parameter Among them, q 12 ,q 21 , r 12 , r 21 is a fixed value; q 11 ,q 22 , r 11 , r 22 The parameters adjusted according to the current vehicle speed include: q 11 =p1+λ1v q 22 =p2+λ2v r 11 =p3+λ3v r 22 =p4+λ4v In the above four equations, p1, p2, p3, and p4 are all proportional constants, λ1, λ2, λ3, and λ4 are all adaptive factors, and v is the current vehicle speed.

11. The vehicle control method according to claim 6, characterized in that: Based on the adjusted weight parameters, combined with the preset Riccati equation and the preset two-degree-of-freedom steering model, the optimal weight matrix is ​​obtained, including: Based on the adjusted weight parameters, updating the system matrix extracted from the preset two-degree-of-freedom steering model; Substituting the updated system matrix, the input matrix and the adjusted weight parameters into the preset Riccati equation for calculation to obtain a solution of the preset Riccati equation, wherein the input matrix is ​​extracted from the preset two-degree-of-freedom steering model; The optimal weight matrix is ​​obtained by calculation based on the solution of the preset Riccati equation.

12. The vehicle control method according to claim 11, characterized in that: According to the optimal weight matrix, the state feedback is substituted into the preset cost function for calculation to obtain the expected rear wheel steering angle value, including: The optimal weight matrix Substitute the state feedback u=-Kx into the preset cost function for calculation to obtain the rear wheel expected turning angle value δ r The operation formula is: d r =-(k 21 b+k 22 w r ) In the above formula, β represents the center of mass sideslip angle, w r represents the yaw angular velocity; The x represents the input of the cost function, namely: the sideslip angle of the center of mass and the yaw rate; The value of u is determined by the optimal weight matrix and the current vehicle state, and the current vehicle state includes: the yaw rate and the executed sideslip angle of the current vehicle.

13. The vehicle control method according to claim 12, characterized in that: When the current vehicle speed is low, the weight of the center of mass sideslip angle in the calculation of the expected rear wheel turning angle value is greater than the weight of the yaw angular velocity; When the current vehicle speed is high, the weight of the yaw rate in the calculation of the expected rear wheel turning angle value is greater than the weight of the center of mass sideslip angle.

14. The vehicle control method according to claim 1, characterized in that: Controlling the rotation of the rear wheels according to the expected rear wheel turning angle value includes: Converting the expected rear wheel turning angle value to obtain the rear wheel lead screw displacement; Based on the displacement of the rear wheel screw, the rotation of the rear wheel is controlled by controlling the movement of the transmission mechanism.

15. A vehicle control device, characterized in that: The vehicle control device comprises: A rear wheel desired steering angle value determination module is used to determine the vehicle's rear wheel desired steering angle value according to the acquired vehicle's current yaw angular velocity, lateral acceleration and longitudinal velocity; The rear wheel rotation control module is used to control the rear wheel rotation according to the rear wheel expected rotation angle value.

16. An electronic device, characterized in that: The electronic device includes a processor and a memory, the memory stores a computer program, and the processor executes the computer program so that the electronic device performs the vehicle control method according to any one of claims 1 to 14.

17. A vehicle, characterized in that: The vehicle includes the vehicle control device according to claim 15 or the electronic device according to claim 16.

18. A readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps in the vehicle control method as described in any one of claims 1 to 14 are implemented.

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