Vehicle control method, device and vehicle

Abstract

A vehicle control method and device and a vehicle are disclosed, and relate to the technical field of automobile chassis electric control. The method comprises the following steps: based on a vehicle dynamics model and a tire model, an EKF filtering algorithm is used to determine the adhesion coefficient between the wheel and the road surface, the adhesion coefficient estimation accuracy and real-time performance are improved; according to the mapping mechanism between the determined adhesion coefficient and the control factor, when the road condition of the vehicle changes, the problem of discontinuous vehicle dynamic response at the working condition junction can be avoided; through the double-reference curve of safety priority, the rear wheel steering angle is determined by linear interpolation, so that the output steering angle is always matched with the current tire available lateral force, the steering control is avoided to be too active, and the robustness and stability of the rear wheel steering control under the complex and changeable road surface environment are improved.

Description

Technical Field

[0001] This application relates to the field of automotive chassis electronic control technology, and more specifically, to a vehicle control method, device, and vehicle. Background Technology

[0002] With the continuous development of autonomous driving and intelligent assisted driving technologies, consumers are placing higher demands on vehicle safety, stability, and handling performance. A vehicle's actual dynamic performance is greatly influenced by road conditions. Traditional rear-wheel steering control strategies typically assume constant road conditions and cannot dynamically adjust to real-time changes in road adhesion. While such control strategies may perform well on dry roads, on low-traction surfaces, excessive rear-wheel steering angles can exacerbate tire slippage, disrupt the vehicle's dynamic balance, and lead to a decrease in handling performance, posing serious safety hazards.

[0003] Therefore, there is a problem of insufficient robustness and stability of rear wheel steering control under complex and variable road conditions. Summary of the Invention

[0004] In view of this, embodiments of this application propose a vehicle control method, device, and vehicle that can realize real-time perception of road conditions and dynamic adjustment of control strategies, and achieve optimal vehicle handling performance under different road conditions.

[0005] The following technical solution is adopted in this application.

[0006] In a first aspect, embodiments of this application provide a vehicle control method applied to a vehicle's steering control unit, the method comprising:

[0007] The system acquires the coefficient of friction between the wheels and the road surface, the vehicle speed, and the front wheel steering angle. Based on the coefficient of friction falling within a threshold range, it determines the larger of a first control factor and a second control factor as the target control factor. The first control factor is negatively correlated with the coefficient of friction; the second control factor is positively correlated with the coefficient of friction. Before the coefficient of friction reaches an intersection value, the target control factor is negatively correlated with the coefficient of friction; after the coefficient of friction reaches an intersection value, the target control factor is positively correlated with the coefficient of friction. Based on the target control factor and the vehicle speed, and using the first and second control factors, it determines the angle ratio between the front and rear wheels of the vehicle. The angle ratio between the front and rear wheels is an estimated value between the first and second control factors, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor. Based on the angle ratio between the front and rear wheels and the target rear wheel steering angle determined by the front wheel steering angle, the system controls the vehicle's steering.

[0008] In some embodiments, obtaining the coefficient of adhesion between the wheel and the road surface includes: Acquire vehicle status data, including vehicle speed, front wheel steering angle, center of gravity sideslip angle, and yaw rate; input the status data into the tire model to determine the vehicle's longitudinal normalized force and lateral normalized force; and determine the adhesion coefficient between the wheel and the road surface based on the longitudinal normalized force and lateral normalized force.

[0009] In some embodiments, the threshold range is from a first threshold to a second threshold, and determining the larger of the first control factor and the second control factor as the target control factor based on the adhesion coefficient being within the threshold range further includes: Based on the adhesion coefficient being lower than a first threshold, the vehicle is determined to be on a first type of adhesion surface, and the first control factor is determined to be 1; based on the vehicle being on a first type of adhesion surface, and based on the adhesion coefficient being higher than or equal to a second threshold, the first control factor is determined to be 0.

[0010] In some embodiments, determining the larger of the first control factor and the second control factor as the target control factor based on the adhesion coefficient being within a threshold range further includes: Based on the adhesion coefficient being higher than or equal to a first threshold, the vehicle is determined to be on a second type of adhesion surface, and the second control factor is determined to be 0; based on the vehicle being on a second type of adhesion surface, and based on the adhesion coefficient being higher than or equal to the second threshold, the second control factor is determined to be 1.

[0011] In some embodiments, before determining the angle ratio of the front and rear wheels of the vehicle, the method further includes: Based on the vehicle being on a first type of surface with adhesion and the target control factor being 1, the first control curve is determined by the relationship between the vehicle speed and the ratio of the front and rear wheel angles according to the front wheel steering angle and a two-dimensional lookup table.

[0012] In some embodiments, before determining the angle ratio of the front and rear wheels of the vehicle, the method further includes: Based on the fact that the vehicle is on a second type of surface with adhesion and the target control factor is 1, the correspondence between the vehicle speed and the ratio of the front and rear wheel angles is determined as the second control curve according to the front wheel steering angle and a two-dimensional lookup table.

[0013] In other embodiments, determining the front-to-rear wheel angle ratio of the vehicle based on the target control factor and the vehicle speed, and based on the first control factor and the second control factor, includes: Based on the first control curve and the second control curve, determine the first control factor and the second control factor corresponding to the vehicle speed; based on the first control factor and the second control factor, establish an estimation function between the target control factor and the angle ratio of the front and rear wheels; based on the target control factor and the estimation function, determine the angle ratio of the front and rear wheels of the vehicle.

[0014] In some embodiments, controlling the vehicle steering based on the target rear wheel steering angle determined by the front and rear wheel angle ratio and the front wheel steering angle includes: Based on the front wheel steering angle, the vehicle speed, and a two-dimensional lookup table, the initial rear wheel steering angle is determined according to the ratio of the front and rear wheel angles; the initial rear wheel steering angle is corrected according to the yaw rate and the vehicle speed to obtain the target rear wheel steering angle; the vehicle steering is controlled according to the target rear wheel steering angle.

[0015] Secondly, embodiments of this application provide a vehicle control device applied to a vehicle's steering control unit, the device comprising: The system includes: an acquisition module for acquiring the coefficient of friction between the wheels and the road surface, the vehicle speed, and the front wheel steering angle; a first processing module for determining a target control factor based on the coefficient of friction falling within a threshold range, where the larger of a first control factor and a second control factor is a target control factor; the first control factor is negatively correlated with the coefficient of friction; the second control factor is positively correlated with the coefficient of friction; wherein, before the coefficient of friction reaches an intersection value, the target control factor is negatively correlated with the coefficient of friction; after the coefficient of friction reaches an intersection value, the target control factor is positively correlated with the coefficient of friction; a second processing module for determining the front-to-rear wheel angle ratio of the vehicle based on the target control factor and the vehicle speed, using the first and second control factors; the front-to-rear wheel angle ratio is an estimated value between the first and second control factors, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor; and a control module for controlling the vehicle steering based on the target rear wheel steering angle determined by the front-to-rear wheel angle ratio and the front wheel steering angle.

[0016] Thirdly, embodiments of this application provide a vehicle, which includes: a control unit; and a memory storing computer-readable instructions, which, when executed by the control unit, implement the control method described above.

[0017] In the solution of this application, firstly, the adhesion coefficient between the wheel and the road surface is determined by the vehicle's state data, based on the vehicle dynamics model, the tire model, and the EKF filtering algorithm, which improves the accuracy of the adhesion coefficient estimation and ensures the real-time performance of the adhesion coefficient estimation. Secondly, the correlation between the adhesion coefficient and the control factor is determined according to the threshold range of the adhesion coefficient, which solves the problem of discontinuous vehicle dynamic response at the working condition boundary when the road conditions change.

[0018] Furthermore, based on the first and second control factors, dual reference curves are generated. According to the target control factor and vehicle speed, linear interpolation is used to determine the angle ratio of the front and rear wheels of the vehicle. Combined with the front wheel steering angle to determine the target rear wheel steering angle, the vehicle steering is controlled to ensure that the output steering angle always matches the available lateral force of the current tires, avoids excessive vehicle steering control, achieves optimal vehicle handling performance under different road conditions, and realizes the synergistic optimization of safety, stability and handling under the full adhesion spectrum.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0021] Figure 1 This is a schematic diagram of a vehicle control system provided in an embodiment of this application.

[0022] Figure 2 This is a schematic flowchart of a vehicle control method provided in an embodiment of this application.

[0023] Figure 3 This is a flowchart illustrating a method for obtaining the adhesion coefficient provided in an embodiment of this application.

[0024] Figure 4 This is a flowchart illustrating a method for determining the relationship between control factors and adhesion coefficients, provided in an embodiment of this application.

[0025] Figure 5 This is a flowchart illustrating a method for determining a control curve, as provided in an embodiment of this application.

[0026] Figure 6 This is a flowchart illustrating a method for determining the target steering angle of the rear wheels, provided in an embodiment of this application.

[0027] Figure 7 This is a schematic diagram of an adhesion coefficient estimation model provided in an embodiment of this application.

[0028] Figure 8 This is a schematic diagram illustrating the variation of a control factor with the adhesion coefficient, provided as an embodiment of this application.

[0029] Figure 9 This is a schematic diagram of a dual-reference control curve provided in an embodiment of this application.

[0030] Figure 10 This is a schematic diagram illustrating how to obtain the target steering angle of the rear wheels, as provided in an embodiment of this application.

[0031] Figure 11 This is a schematic diagram of the structure of a vehicle control device provided in an embodiment of this application.

[0032] Figure 12 This is a schematic diagram of the vehicle structure provided in an embodiment of this application.

[0033] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through specific embodiments. Detailed Implementation

[0034] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0035] In conventional technologies, vehicle control strategies that assume constant road conditions or employ simple friction coefficient estimation models struggle to cope with sudden road surface changes, resulting in significant limitations in practical applications. This is particularly true on wet or icy surfaces, where it can easily lead to tire slippage, loss of control, and even traffic accidents. Friction coefficient estimation primarily relies on data collected by devices such as wheel speed sensors and acceleration sensors, processed through complex filtering algorithms and pattern recognition techniques to accurately assess the current road conditions. However, despite advancements in friction coefficient estimation technology, the challenge remains of effectively integrating these estimation results into the vehicle control system and achieving rapid and accurate dynamic adjustments.

[0036] The vehicle control method provided in this application aims to solve the above-mentioned technical problems of the prior art.

[0037] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0038] Figure 1 This is a schematic diagram of a vehicle control system provided as an embodiment of this application. Figure 1 As shown, the vehicle control system 100 provided in this embodiment includes a sensor module 101, an estimation module 102, a rear wheel steering angle generation module 103, and a rear wheel steering execution module 104. The estimation module 102 includes a vehicle dynamics model 112 and a tire model 122, and the rear wheel steering angle generation module 103 includes a control factor generation module 113 and a rear wheel steering angle calculation module 123.

[0039] In one alternative implementation, the sensor module 101 and the rear wheel steering actuation module 104 refer to hardware devices. The sensor module 101 includes, but is not limited to, a front wheel steering angle sensor and four-wheel wheel speed sensors, while the rear wheel steering actuation module 104 includes, but is not limited to, a drive motor and steering tie rods.

[0040] In another alternative implementation, the estimation module 102 and the rear wheel steering angle generation module 103 refer to software units or modules. Specifically, the estimation module 102 estimates the coefficient of friction between the vehicle's tires and the road surface, and the rear wheel steering angle generation module 103 determines the rear wheel steering angle of the vehicle based on the coefficient of friction.

[0041] The following is combined Figure 1 The vehicle control system 100 shown illustrates the vehicle control method provided in this application embodiment: the vehicle's state data is acquired through the sensor module 101, including at least vehicle speed, front wheel steering angle, center of gravity sideslip angle, and yaw rate. The state data is input into the vehicle dynamics model 112 in the estimation module 102 to calculate the vehicle's yaw acceleration, lateral acceleration, and longitudinal acceleration. The calculated data is then input into the tire model 122 in the estimation module 102 to obtain the vehicle's longitudinal normalized force and lateral normalized force. The adhesion coefficient between the wheel and the road surface is estimated based on the longitudinal normalized force and lateral normalized force.

[0042] In addition, the adhesion coefficient is input into the control factor generation module 113 to determine the correspondence between the adhesion coefficients and control factors of the first type of adhesion road surface and the second type of adhesion road surface, thereby obtaining the first control factor of the first type of adhesion road surface and the second control factor of the second type of adhesion road surface; the rear wheel steering angle generation module 103 takes the larger value between the first control factor and the second control factor as the target control factor; the rear wheel steering angle calculation module 123 determines the angle ratio of the front and rear wheels of the vehicle based on the target control factor and the vehicle speed; the rear wheel steering angle generation module 103 determines the target rear wheel steering angle based on the angle ratio of the front and rear wheels and the obtained front wheel steering angle; the rear wheel steering angle generation module 103 sends the target rear wheel steering angle to the rear wheel steering execution module 104 to control the vehicle to complete the steering.

[0043] Below Figure 1 Based on the vehicle control system 100 shown, the vehicle control method provided in the embodiments of this application will be further described, such as... Figure 2 The diagram shown illustrates a vehicle control method. In a specific embodiment, this vehicle control can be applied to, for example... Figure 11 The vehicle control device 700 and the vehicle 800 equipped with the vehicle control device 700 are shown. Figure 12 The specific process of the embodiments of this application will be described below. Of course, it is understood that this method can be executed by a cloud server with computing power. The following will focus on... Figure 2 The process shown is described in detail and applied to the vehicle's steering control unit. The vehicle control method may specifically include the following steps 201 to 204.

[0044] Step 201: Obtain the adhesion coefficient between the wheel and the road surface, the vehicle speed, and the front wheel steering angle.

[0045] In the embodiments of this application, the coefficient of adhesion represents the vehicle's grip capability under different road surface conditions.

[0046] For example, to ensure high efficiency and real-time data transmission, the vehicle communicates with various sensors via CANFD (Controller Area Network Flexible Data-rate), including but not limited to the front wheel steering angle sensor and four-wheel wheel speed sensors. The sensors transmit the acquired data to the vehicle's steering control unit for processing, including the front wheel steering angle and the wheel speeds of the four wheels.

[0047] For example, since different sensors update data at different frequencies and send data at different times (e.g., wheel speed may be 10ms / frame, steering angle may be 20ms / frame), before preprocessing the sensor data, it is necessary to add a hardware timestamp to each data point and then use interpolation, extrapolation, and synchronization to a unified time to ensure that all data participate in the calculation under the same time reference, thereby avoiding distortion in subsequent vehicle dynamics calculations. After the sensor data is aligned with the timestamp, it can be preprocessed using low-pass filtering, median filtering, amplitude limiting, outlier detection and removal, etc., to filter out high-frequency noise, remove spikes and glitches, achieve smooth and stable data signals, and improve the signal-to-noise ratio of the data.

[0048] Furthermore, the synchronized and filtered sensor data is packaged at fixed intervals (e.g., 10ms) and used as input to the vehicle state estimation algorithm. The state estimation algorithm can employ the Extended Kalman Filter (EKF) algorithm.

[0049] For example, such as Figure 7 The diagram shows a model for estimating the coefficient of adhesion. Based on a vehicle dynamics model and a tire model, it uses the EKF filtering algorithm to fuse sensor data such as the front wheel steering angle, the wheel speed of the four wheels, longitudinal / lateral acceleration, and yaw rate to estimate the coefficient of adhesion between the four wheels and the road surface in real time.

[0050] Optionally, the vehicle dynamics model adopts a nonlinear seven-degree-of-freedom vehicle dynamics model, which uses packaged sensor data (such as front wheel steering angle and wheel speed of the four wheels) and the vehicle's own parameters (such as wheelbase and track width) to calculate the vehicle's longitudinal acceleration, lateral acceleration and yaw acceleration.

[0051] Optionally, the tire model uses Dugoff, taking the vehicle's longitudinal acceleration, lateral acceleration, yaw acceleration, vehicle speed, wheel speeds of the four wheels, front wheel steering angle, and center of gravity sideslip angle as inputs to calculate the vehicle's longitudinal normalized force and lateral normalized force.

[0052] Furthermore, the longitudinal and lateral normalized forces of the vehicle are used as inputs to the EKF algorithm, and then the system measurement equation y(t)=h(x) is established. p (t),u(t),v(t)), where, x p Let y(t) be the parameter variable, y(t) be the measurement variable, u(t) be the control input variable, and v(t) be the sensor variable. Then, the adhesion coefficient μ between the four wheels of the vehicle and the road surface is calculated using the Jacobian matrix and the EKF filtering algorithm. ij .

[0053] Step 202: Based on the adhesion coefficient being within a threshold range, determine the larger of the first control factor and the second control factor as the target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient.

[0054] In this embodiment of the application, the threshold range of the adhesion coefficient is (0.3, 0.8); the first control factor is determined based on the adhesion coefficient of the first type of adhesion road surface, the second control factor is determined based on the adhesion coefficient of the second type of adhesion road surface, and the target control factor is the larger value between the first control factor and the second control factor determined based on the same adhesion coefficient.

[0055] In the first optional example, road surfaces with an adhesion coefficient less than 0.3 are classified as Class I adhesion road surfaces, and those with an adhesion coefficient greater than or equal to 0.3 are classified as Class II adhesion road surfaces. For example... Figure 8 The diagram illustrates how a control factor varies with the adhesion coefficient. To ensure a smooth transition rather than abrupt changes in the adhesion coefficient near a critical point (e.g., a critical point value of 0.3), and to avoid discontinuous vehicle dynamic response at the boundary between different operating conditions, the following approach is adopted: Figure 8 The curves shown represent the relationship between the control factor and the adhesion coefficient for the first type of adhesion pavement, which is represented by the curve for the low adhesion factor. The curves represent the relationship between the control factor and the adhesion coefficient for the second type of adhesion pavement, which is represented by the curve for the normal adhesion factor.

[0056] Among them, the control factor f of the first type of adhesion pavement low The relationship between (μ) and the adhesion coefficient μ can be expressed by formula (1), such as Figure 8 The curve represented by the low-adjacent factor shown.

[0057] Formula (1) Among them, the control factor f of the second type of adhesion pavement norm The relationship between (μ) and the adhesion coefficient can be expressed by formula (2), such as Figure 8 The curve represented by the normal adhesion factor is shown.

[0058] Formula (2) Further, based on the adhesion coefficient determined in step 201 and Figure 8As shown by the curve, when the adhesion coefficient is in the threshold range (0.3, 0.8), since the curves have overlapping areas, the larger of the first control factor for the first type of adhesion road surface and the second control factor for the second type of adhesion road surface corresponding to the same adhesion coefficient is taken as the target control factor, so as to determine the angle ratio of the front and rear wheels.

[0059] For example, the adaptive adjustment of the control strategy is realized through the continuous mapping mechanism of control factor-adhesion coefficient. The control factor (f(μ)∈[0,1]) expressed by a monotonically increasing / decreasing function directly maps the adhesion coefficient of the road surface to the control weight coefficient of the vehicle, which solves the problem of discontinuous dynamic response of the vehicle at the working condition boundary when the road surface where the vehicle is located switches from the first type of adhesion road surface to the second type of adhesion road surface.

[0060] Step 203: Based on the target control factor and the vehicle speed, determine the angle ratio of the front and rear wheels of the vehicle based on the first control factor and the second control factor; the angle ratio of the front and rear wheels is an estimated value based on the first control factor and the second control factor, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor.

[0061] In the embodiments of this application, such as Figure 9 The diagram shows a dual-reference control curve. Based on the control factor, the angle ratio between the front and rear wheels and the vehicle speed are pre-set as dual-reference control curves. One is the SNOW / ICE control curve applicable to the first type of adhesion road surface (low adhesion road surface), and the other is the TOUR control curve applicable to the second type of adhesion road surface (normal adhesion road surface).

[0062] Among them, the SNOW / ICE control curve is the curve showing how the front and rear wheel angle ratio changes with vehicle speed when the adhesion coefficient of the low-adhesion road surface is between 0 and 0.3, that is, when the first control factor is 1; the TOUR control curve is the curve showing how the front and rear wheel angle ratio changes with vehicle speed when the adhesion coefficient of the normal-adhesion road surface is between 0.8 and 1, that is, when the second control factor is 0.

[0063] When the control factor is 0 or 1, the relationship between the front and rear wheel angle ratio and vehicle speed can be determined by looking up a two-dimensional table based on vehicle speed. Specifically, first, the vehicle's steering wheel angle is obtained, and then converted into the actual front wheel steering angle using the angular transmission ratio and steering geometry. Based on the front wheel steering angle and vehicle speed, the corresponding rear wheel steering angle is determined using a two-dimensional table. Next, the correction coefficient for the rear wheel steering angle is determined by looking up the obtained yaw rate. After amplitude and rate of change limiting, the rear wheel steering angle is obtained. Combining this with the front wheel steering angle generates the SNOW / ICE control curve and the TOUR control curve.

[0064] Furthermore, the SNOW / ICE control curve and the TOUR control curve are used as dual reference control curves for vehicle control. The target control factor currently acquired by the vehicle determines which curve to use for control output. If the value of the control factor gradually changes between the SNOW / ICE control curve and the TOUR control curve, then linear interpolation is used to determine the angle ratio of the front and rear wheels.

[0065] For example, the vehicle's current speed is acquired in real time, and the output values ​​of the SNOW / ICE control curve and TOUR control curve corresponding to that speed are determined. The output values ​​of the SNOW / ICE control curve and TOUR control curve are linearly interpolated according to the target control factor to calculate the angle ratio of the front and rear wheels of the vehicle under the current operating condition.

[0066] Step 204: Based on the angle ratio of the front and rear wheels and the target steering angle of the rear wheels determined by the front wheel steering angle, control the vehicle steering.

[0067] In this embodiment, based on the SNOW / ICE control curve and the TOUR control curve, and according to the principle that the larger of the first control factor and the second control factor is the target control factor, when the adhesion coefficient is between 0 and 0.3, the target control factor is set to 1. The vehicle then proceeds according to... Figure 9 The control output is based on the SNOW / ICE control curve shown; when the adhesion coefficient is between 0.8 and 1, the target control factor is set to 1, and the vehicle controls according to the following... Figure 9 The TOUR control curve shown is used for control output; in addition, when the adhesion coefficient is between 0.3 and 0.8, the value of the target control factor first decreases monotonically and then increases monotonically. It can be seen that the angle ratio of the front and rear wheels is between the two reference curves. The vehicle uses linear interpolation to obtain the angle ratio of the front and rear wheels based on the current vehicle speed for control output.

[0068] The target rear wheel steering angle can be determined by the ratio of the front and rear wheel angles and the front wheel steering angle.

[0069] For example, in order to eliminate the jitter in the estimation of the road surface adhesion coefficient, it is necessary to limit both the amplitude and the rate of change of the adhesion coefficient. Based on the judgment that different road surface adhesion coefficients correspond to different rear wheel steering angles, different control strategies are adopted. Among them, on low-adhesion road surfaces, not only is the steering angle amplitude limited, but the gain of high-speed same-direction steering is also actively attenuated to prevent excessive yaw moment.

[0070] Optionally, when the vehicle is at low speed, the rear wheels are in the opposite direction to the front wheels to reduce the turning radius and enhance steering flexibility. If the vehicle is on a low-friction surface, the rear wheel angle is suppressed to limit the wheel slip range.

[0071] Optionally, when the vehicle is at high speed, the rear wheels are in the same direction as the front wheels, increasing the turning radius and improving vehicle stability. If the vehicle is on a low-friction surface, the rear wheel angle is allowed to be even greater, further improving driving stability.

[0072] For example, after determining the current target rear wheel steering angle of the vehicle, a whole vehicle simulation model can be built using the CarSim / Simulink co-simulation platform to simulate rear wheel steering control under conditions such as open road surface and double lane change on snow, to verify the effectiveness of the control strategy, and to verify it through a real vehicle test track and perform closed-loop feedback verification.

[0073] In this embodiment, firstly, based on the vehicle dynamics model and tire model, the EKF filtering algorithm is used to determine the adhesion coefficient between the wheel and the road surface, which improves the accuracy of the adhesion coefficient estimation while ensuring the real-time performance of the adhesion coefficient estimation. Secondly, according to the mapping mechanism between the adhesion coefficient and the control factor, the road surface adhesion state, which cannot be directly measured, is transformed into a quantifiable, mappable, and executable control weight, thereby driving the rear wheel steering to dynamically optimize within the safety boundary, solving the problem of discontinuous vehicle dynamic response at the working condition boundary when the road conditions change.

[0074] In addition, a dual-reference curve interpolation-based rear-wheel steering target generation architecture prioritizing safety is established, which resolves the fundamental contradiction of "stability and agility being mutually exclusive" on complex road surfaces, ensuring that the output steering angle always matches the available lateral force of the current tire and avoiding over-control. Finally, the introduction of the adhesion coefficient as a dual criterion for directional decision and amplitude limiting is proposed to further improve the robustness of vehicle control at the boundary under extreme conditions.

[0075] Regarding how to obtain the coefficient of adhesion between the wheel and the road surface, embodiments of this application provide an optional implementation method, such as... Figure 3 The flowchart shown is a method for obtaining the adhesion coefficient, which may specifically include the following steps 301 to 307.

[0076] Step 301: Obtain vehicle status data, including vehicle speed, front wheel steering angle, center of gravity sideslip angle, and yaw rate.

[0077] In this embodiment of the application, the front wheel steering angle is obtained in real time by the front wheel steering angle sensor and the four wheel speed sensors are obtained in real time by the four wheel speed sensors. The longitudinal acceleration, lateral acceleration and yaw acceleration of the vehicle are calculated by the front wheel steering angle, the four wheel speeds and the vehicle's own parameters (such as wheelbase and track width).

[0078] The longitudinal acceleration can be calculated using the following formula (3). ax .

[0079] Formula (3) Similarly, the lateral acceleration can be obtained. a y .

[0080] The yaw acceleration can be calculated using the following formula (4). .

[0081]

[0082] in, Longitudinal acceleration (m / ); Lateral acceleration (m / ); Yaw acceleration (rad / ), which is the rotational acceleration of the vehicle about its vertical axis.

[0083] in, : Tire longitudinal force (N) : Tire lateral force (N); subscript ij Indicates tire position ( Left front, Right front, Left rear, (Right rear) The superscript 0 indicates the reference state or the force after linearization.

[0084] in, Distance from the front axle to the vehicle's center of gravity (m); b Distance from the rear axle to the vehicle's center of gravity (m); Front wheel track (center-to-center distance between front wheels, meters); Rear wheel track (center-to-center distance between front wheels, meters); Moment of inertia of a vehicle about its vertical axis (kg· ); Front wheel steering angle.

[0085] in, : Coefficient of adhesion between tire and road surface, subscript ij Indicates tire position ( Left front, Right front, Left rear, (Right rear) Normalized tire force.

[0086] Step 302: Input the state data into the tire model to determine the longitudinal normalized force and lateral normalized force of the vehicle.

[0087] In this embodiment of the application, the calculated longitudinal acceleration, lateral acceleration and yaw acceleration of the vehicle are input into the tire model, and the longitudinal normalized force can be obtained by the following formula (5) and the lateral normalized force can be obtained by formula (6).

[0088] Formula (5) Formula (6) in, The force generated by the tire in the longitudinal direction, The force generated by the tire in the lateral direction can be either driving force or braking force; The coefficient of adhesion between the tire and the road surface; : Maximum possible friction (adhesion limit); The effect of slip ratio on longitudinal force; The effect of slip ratio on lateral force.

[0089] in, f(L) : Combined slip correction factor, which describes the force attenuation of the tire during combined slip (simultaneous longitudinal and lateral slip); L is a dimensionless variable used to determine whether the adhesion limit has been reached. When L≥1, the tire is in a pure slip or small slip state and the force is not attenuated; when L<1, the tire is in a combined slip state and the force attenuates according to L(2-L).

[0090] Step 303: Determine the adhesion coefficient between the wheel and the road surface based on the longitudinal normalized force and the lateral normalized force.

[0091] For example, by establishing system measurement equations Parameter variables Measurement Variables , Input variables are controlled by sensor variables. δ is the front wheel steering angle. The road adhesion coefficient is calculated using the Jacobian matrix and the EKF filtering algorithm. .

[0092] Step 304: Obtain the vehicle speed and front wheel steering angle.

[0093] Step 305: Based on the adhesion coefficient being within a threshold range, determine the larger of the first control factor and the second control factor as the target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient.

[0094] Step 306: Based on the target control factor and the vehicle speed, determine the angle ratio of the front and rear wheels of the vehicle based on the first control factor and the second control factor; the angle ratio of the front and rear wheels is an estimated value based on the first control factor and the second control factor, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor.

[0095] Step 307: Based on the angle ratio of the front and rear wheels and the target steering angle of the rear wheels determined by the front wheel steering angle, control the vehicle steering.

[0096] The specific steps of steps 304 to 307 can be found in steps 201 to 204, and will not be repeated here.

[0097] In this embodiment, a nonlinear seven-degree-of-freedom vehicle dynamics model is established, which achieves higher accuracy while ensuring real-time performance. It can accurately describe the dynamic behavior of the vehicle under extreme conditions. Combined with the tire model, the EKF filtering algorithm is used to determine the adhesion coefficient between the wheel and the road surface, which improves the accuracy of the adhesion coefficient estimation while ensuring the real-time performance of the adhesion coefficient estimation.

[0098] Based on the above, this application provides an optional implementation method for determining the variation law between the control factor and the adhesion coefficient, which may specifically include the following steps 401 to 404.

[0099] Step 401: Obtain the adhesion coefficient between the wheel and the road surface, the vehicle speed, and the front wheel steering angle.

[0100] Step 402: Based on the adhesion coefficient being within a threshold range, determine the larger of the first control factor and the second control factor as the target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient.

[0101] Wherein, the threshold interval in step 402 is from the first threshold to the second threshold, such as Figure 4 The flowchart shown is a method for determining the relationship between control factor and adhesion coefficient. When the adhesion coefficient is not in the threshold range, it may further include the following steps 412 to 442.

[0102] Step 412: Based on the fact that the adhesion coefficient is lower than the first threshold, determine that the vehicle is on a first type of adhesion surface and determine that the first control factor is 1.

[0103] In this embodiment of the application, the first threshold is 0.3 and the second threshold is 0.8. Based on the real-time estimated road surface adhesion coefficient, the driving road surface is dynamically divided into two categories. When the adhesion coefficient is less than 0.3, it is determined to be a low-adhesion road surface (first type of adhesion road surface). According to formula (1), when the adhesion coefficient is less than 0.3, the first control factor is determined to be 1.

[0104] Step 422: Based on the fact that the vehicle is on a first type of adhesion surface, and according to the adhesion coefficient being higher than or equal to the second threshold, the first control factor is determined to be 0.

[0105] In this embodiment of the application, when the road surface is determined to be low-adhesion road surface (first type of adhesion road surface), the first control factor is also determined to be 0 when the adhesion coefficient is greater than 0.8 according to formula (1).

[0106] Step 432: Based on the adhesion coefficient being higher than or equal to the first threshold, determine that the vehicle is on a second type of adhesion surface and determine that the second control factor is 0.

[0107] In this embodiment of the application, when the adhesion coefficient is higher than or equal to 0.3, it is determined to be a normal adhesion road surface (second type of adhesion road surface). According to formula (2), when the adhesion coefficient is less than 0.3, the first control factor is determined to be 0.

[0108] Step 442: Based on the fact that the vehicle is on a second type of adhesion surface, and according to the adhesion coefficient being higher than or equal to the second threshold, the second control factor is determined to be 1.

[0109] In this embodiment of the application, when the road surface is determined to be a normal adhesion road surface (second type of adhesion road surface), the first control factor is determined to be 1 when the adhesion coefficient is greater than 0.8 according to formula (2).

[0110] Furthermore, when the adhesion coefficient is in the threshold range (0.3, 0.8), it can be seen that... Figure 8 Before the intersection point of the curves shown, the first control factor of the first type of adhesion pavement is used as the target control factor, and in Figure 8 After the intersection point of the regular curves shown, the second control factor of the second type of attached pavement is used as the target control factor.

[0111] Step 403: Based on the target control factor and the vehicle speed, determine the angle ratio of the front and rear wheels of the vehicle based on the first control factor and the second control factor; the angle ratio of the front and rear wheels is an estimated value based on the first control factor and the second control factor, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor.

[0112] Step 404: Based on the angle ratio of the front and rear wheels and the target steering angle of the rear wheels determined by the front wheel steering angle, control the vehicle steering.

[0113] The specific steps of steps 401, 403 to 404 can be found in steps 201, 203 to 204, and will not be repeated here.

[0114] In this embodiment, based on the mapping mechanism between the adhesion coefficient and the control factor, the road adhesion state, which cannot be directly measured, is transformed into a quantifiable, mappable, and executable control weight, thereby driving the rear wheel steering to dynamically optimize within the safety boundary. This solves the problem of discontinuous vehicle dynamic response at the interface of working conditions when the road conditions change.

[0115] Based on the above, before determining the angle ratio of the front and rear wheels of the vehicle, a dual reference curve for the control factors is generated according to the first type of adhesion road surface and the second type of adhesion road surface to facilitate the subsequent acquisition of the front and rear wheel angle ratio. This application provides an optional implementation method, such as... Figure 5 The flowchart shown is a method for determining a control curve, which may specifically include the following steps 501 to 508.

[0116] Step 501: Obtain the adhesion coefficient between the wheel and the road surface, the vehicle speed, and the front wheel steering angle.

[0117] Step 502: Based on the adhesion coefficient being within a threshold range, determine the larger of the first control factor and the second control factor as the target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient.

[0118] Step 503: Based on the vehicle being on a first type of surface with adhesion and the target control factor being 1, the first control curve is determined by the front wheel steering angle and a two-dimensional lookup table to establish the correspondence between the vehicle speed and the ratio of the front and rear wheel angles.

[0119] In this embodiment, the nonlinear seven-degree-of-freedom vehicle dynamics optimization results are pre-calculated and stored in a table (two-dimensional table). When the vehicle performs control actions, the output is directly determined by looking up the table, eliminating the need to solve equations in real time, thereby improving the real-time performance of vehicle control.

[0120] For example, such as Figure 8The curve represented by the low adhesion factor, when the adhesion coefficient is between 0 and 0.3, indicates that the target control factor is 1, meaning the vehicle's control weight coefficient is 1. Based on a pre-calibrated MAP (two-dimensional table), the rear wheel steering angle is directly determined according to the front wheel steering angle and vehicle speed, thereby determining the ratio of the front and rear wheel angles and generating a curve as shown. Figure 9 The first control curve shown is the SNOW / ICE control curve.

[0121] Step 504: Based on the vehicle being on a second type of surface with adhesion and the target control factor being 1, the corresponding relationship between the vehicle speed and the ratio of the front and rear wheel angles is determined as the second control curve according to the front wheel steering angle and a two-dimensional lookup table.

[0122] In the embodiments of this application, such as Figure 8 The curve represented by the normal adhesion factor, when the adhesion factor is between 0.8 and 1, indicates that the target control factor is 1, meaning the vehicle's control weight coefficient is 1. Similarly, based on a pre-calibrated MAP (two-dimensional table), the rear wheel steering angle is directly determined according to the front wheel steering angle and vehicle speed, thereby determining the front-to-rear wheel angle ratio and generating a curve as shown. Figure 9 The second control curve shown is the TOUR control curve.

[0123] Step 505: Determine the first control factor and the second control factor corresponding to the vehicle speed based on the first control curve and the second control curve.

[0124] In this embodiment, the first control curve and the second control curve serve as baselines. Based on the current vehicle speed, the output values ​​of the first control curve and the second control curve corresponding to that speed are determined, namely the first control factor and the second control factor.

[0125] Step 506: Based on the first control factor and the second control factor, establish an estimation function between the target control factor and the angle ratio of the front and rear wheels.

[0126] For example, when the calculated adhesion coefficient is between 0.3 and 0.8, different target control factors are determined according to different adhesion coefficients. Based on the output values ​​of the first control curve and the second control curve corresponding to the current vehicle speed, linear interpolation is used to determine the estimation function between the control factor and the angle ratio of the front and rear wheels.

[0127] Step 507: Based on the target control factor and the estimation function, determine the angle ratio of the front and rear wheels of the vehicle.

[0128] In this embodiment, the angle ratio of the front and rear wheels of the vehicle can be determined by using the target control factor based on the estimation function between the control factor and the angle ratio of the front and rear wheels.

[0129] Step 508: Based on the angle ratio of the front and rear wheels and the target steering angle of the rear wheels determined by the front wheel steering angle, control the vehicle steering.

[0130] The specific steps of steps 501 to 502 and 508 can be found in steps 201 to 202 and 204, and will not be repeated here.

[0131] In this application embodiment, a safety-first dual-reference curve interpolation-based rear wheel steering target generation architecture is established, which solves the fundamental contradiction of "stability and agility cannot be achieved at the same time" on complex road surfaces, ensuring that the output steering angle always matches the available lateral force of the current tire and avoiding over-control.

[0132] Based on the above, this application provides an optional implementation method for controlling the vehicle steering based on the front-to-rear wheel angle ratio and the target rear wheel steering angle determined by the front wheel steering angle, such as... Figure 6 The flowchart shown is a method for determining the target steering angle of the rear wheel, which may specifically include the following steps 601 to 606.

[0133] Step 601: Obtain the adhesion coefficient between the wheel and the road surface, the vehicle speed, and the front wheel steering angle.

[0134] Step 602: Based on the adhesion coefficient being within a threshold range, determine the larger of the first control factor and the second control factor as the target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient.

[0135] Step 603: Based on the target control factor and the vehicle speed, determine the angle ratio of the front and rear wheels of the vehicle based on the first control factor and the second control factor; the angle ratio of the front and rear wheels is an estimated value based on the first control factor and the second control factor, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor.

[0136] Step 604: Determine the initial steering angle of the rear wheels based on the front wheel steering angle, the vehicle speed, and a two-dimensional lookup table, using the angle ratio of the front and rear wheels.

[0137] In the embodiments of this application, such as Figure 10 As shown, using the vehicle's current front wheel steering angle and speed as input, the ratio of the front and rear wheel angles is queried to calculate the initial rear wheel steering angle.

[0138] Step 605: Based on the yaw rate and the vehicle speed, correct the initial steering angle of the rear wheels to obtain the target steering angle of the rear wheels.

[0139] In this embodiment of the application, the yaw rate and vehicle speed are used as inputs to query the correction coefficient of the rear wheel steering angle, and the initial steering angle of the rear wheel is corrected to obtain the target steering angle of the rear wheel.

[0140] Step 606: Control the vehicle steering according to the target rear wheel steering angle.

[0141] In this embodiment, the rear wheel steering mechanism is driven according to the target rear wheel steering angle to achieve steering characteristics that are flexible at low speeds, stable at high speeds, and safe with low adhesion.

[0142] The specific steps of steps 601 to 603 can be found in steps 201 to 203, and will not be repeated here.

[0143] To achieve the functions of the above embodiments, the vehicle control method includes hardware structures and / or software modules corresponding to each function. Those skilled in the art should readily recognize that, based on the units and method steps described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0144] exist Figures 2 to 10 Based on the vehicle control method shown, the embodiments of this application also provide a vehicle control device for further explanation, such as... Figure 11 The schematic diagram of the vehicle control device shown includes: an acquisition module 710, a first processing module 720, a second processing module 730, and a control module 740.

[0145] Acquisition module 710 is used to acquire the adhesion coefficient between the wheels and the road surface, the vehicle speed, and the front wheel steering angle; wherein, acquisition module 710 may include, for example, Figure 1 The sensor module 101 and estimation module 102 are shown.

[0146] The first processing module 720 is configured to determine, based on the adhesion coefficient being within a threshold range, a target control factor that is the larger of a first control factor and a second control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficients reach an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficients reach an intersection value, the target control factor is positively correlated with the adhesion coefficient; wherein, the acquisition module 710 may include, for example... Figure 1 The control factor generation module 113 in the rear wheel steering angle generation module 103 shown.

[0147] The second processing module 730 is configured to determine the front-to-rear wheel angle ratio of the vehicle based on the target control factor and the vehicle speed, and on the basis of the first control factor and the second control factor; the front-to-rear wheel angle ratio is an estimated value based on the first control factor and the second control factor, and is the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor; wherein, the second processing module 730 may include, for example, Figure 1 The rear wheel steering angle calculation module 123 in the rear wheel steering angle generation module 103 shown.

[0148] Control module 740 is used to control the vehicle steering based on the rear wheel target steering angle determined by the front wheel angle ratio and the front wheel steering angle; wherein, control module 740 may include, for example, Figure 1 The rear wheel steering execution module 104 is shown.

[0149] In some embodiments, the acquisition module 710 includes: acquiring vehicle state data, the state data including vehicle speed, front wheel steering angle, center of gravity sideslip angle, and yaw rate; inputting the state data into a tire model to determine the longitudinal normalized force and lateral normalized force of the vehicle; and determining the adhesion coefficient between the wheel and the road surface based on the longitudinal normalized force and lateral normalized force.

[0150] In other embodiments, the first processing module 720 includes: determining that the vehicle is on a first type of adhesion surface and determining the first control factor to be 1 based on the adhesion coefficient being lower than a first threshold; and determining the first control factor to be 0 based on the vehicle being on a first type of adhesion surface and the adhesion coefficient being higher than or equal to a second threshold.

[0151] In some embodiments, the first processing module 720 further includes: determining that the vehicle is on a second type of adhesion surface and determining that the second control factor is 0 based on the adhesion coefficient being higher than or equal to a first threshold; and determining that the second control factor is 1 based on the vehicle being on a second type of adhesion surface and the adhesion coefficient being higher than or equal to the second threshold.

[0152] In other embodiments, the second processing module 730 includes: determining a first control curve based on the vehicle being on a first type of surface with adhesion and the target control factor being 1, according to the front wheel steering angle and a two-dimensional lookup table, the corresponding relationship between the vehicle speed and the ratio of the front and rear wheel angles.

[0153] In some embodiments, the second processing module 730 further includes: determining a second control curve based on the vehicle being on a second type of surface with adhesion and the target control factor being 1, according to the front wheel steering angle and a two-dimensional lookup table, the corresponding relationship between the vehicle speed and the ratio of the front and rear wheel angles.

[0154] In some embodiments, the second processing module 730 further includes: determining a first control factor and a second control factor corresponding to the vehicle speed based on the first control curve and the second control curve; establishing an estimation function between the target control factor and the angle ratio of the front and rear wheels based on the first control factor and the second control factor; and determining the angle ratio of the front and rear wheels of the vehicle based on the target control factor and the estimation function.

[0155] In other embodiments, the control module 740 includes: determining an initial rear wheel steering angle based on the front wheel steering angle, the vehicle speed, and a two-dimensional lookup table, and based on the angle ratio of the front and rear wheels; correcting the initial rear wheel steering angle based on the yaw rate and the vehicle speed to obtain a target rear wheel steering angle; and controlling the vehicle steering based on the target rear wheel steering angle.

[0156] According to one aspect of the embodiments of this application, Figure 12 This is a structural schematic diagram of a vehicle provided in an embodiment of this application. Figure 12 As shown, the vehicle 800 includes a control unit 810 and one or more memory units 820. The one or more memory units 820 are used to store program instructions executed by the control unit 810. When the control unit 810 executes the program instructions, it implements the vehicle control method described above.

[0157] Furthermore, the control unit 810 may include one or more processing cores. The control unit 810 runs or executes instructions, programs, code sets, or instruction sets stored in the memory 820, and calls data stored in the memory 820. Optionally, the control unit 810 may be implemented using at least one hardware form selected from Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), and Programmable Logic Array (PLA). The control unit 810 may integrate one or a combination of several of the following: Central Processing Unit (CPU), Graphics Processing Unit (GPU), and Modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the displayed content; and the modem handles wireless communication. It is understood that the modem may also not be integrated into the processor and may be implemented using a separate communication chip.

[0158] According to one aspect of this application, a computer-readable storage medium is also provided, which may be included in the vehicle described in the above embodiments; or it may exist independently and not installed in the vehicle. The computer-readable storage medium carries computer-readable instructions that, when executed by a processor, implement the methods in any of the above embodiments.

[0159] It should be noted that the computer-readable medium shown in the embodiments of this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. Computer-readable storage media can be, for example, but not limited to: electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium can include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such transmitted data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination thereof.

[0160] The units described in the embodiments of this application can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

[0161] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. Each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0162] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0163] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A vehicle control method, characterized in that, The steering control unit used in vehicles includes: Obtain the coefficient of adhesion between the wheels and the road surface, the vehicle speed, and the front wheel steering angle; Based on the adhesion coefficient being within a threshold range, the larger of the first control factor and the second control factor is determined as the target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient. Based on the target control factor and the vehicle speed, and using the first control factor and the second control factor, the angle ratio of the front and rear wheels of the vehicle is determined; the angle ratio of the front and rear wheels is an estimated value between the first control factor and the second control factor, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor. The vehicle steering is controlled based on the front-to-rear wheel angle ratio and the front wheel steering angle.

2. The method according to claim 1, characterized in that, The process of obtaining the coefficient of adhesion between the wheel and the road surface includes: Acquire vehicle status data, including vehicle speed, front wheel steering angle, center of gravity sideslip angle, and yaw rate; The state data is input into the tire model to determine the longitudinal normalized force and lateral normalized force of the vehicle. The adhesion coefficient between the wheel and the road surface is determined based on the longitudinal normalized force and the lateral normalized force.

3. The method according to claim 1, characterized in that, The threshold range is from a first threshold to a second threshold. The method further includes determining the larger of the first control factor and the second control factor as the target control factor based on the adhesion coefficient falling within the threshold range. Based on the adhesion coefficient being lower than a first threshold, the vehicle is determined to be on a first type of adhesion surface, and the first control factor is determined to be 1. Based on the fact that the vehicle is on a first type of adhesion surface, and according to the adhesion coefficient being higher than or equal to the second threshold, the first control factor is determined to be 0.

4. The method according to claim 3, characterized in that, The method further includes determining the larger of the first control factor and the second control factor as the target control factor based on the adhesion coefficient being within a threshold range. Based on the adhesion coefficient being higher than or equal to a first threshold, the vehicle is determined to be on a second type of adhesion surface, and the second control factor is determined to be 0. Based on the fact that the vehicle is on a second type of adhesion surface, and according to the adhesion coefficient being higher than or equal to the second threshold, the second control factor is determined to be 1.

5. The method according to claim 4, characterized in that, Before determining the angle ratio of the front and rear wheels of the vehicle, the method further includes: Based on the vehicle being on a first type of surface with adhesion and the target control factor being 1, the first control curve is determined by the relationship between the vehicle speed and the ratio of the front and rear wheel angles according to the front wheel steering angle and a two-dimensional lookup table.

6. The method according to claim 5, characterized in that, Before determining the angle ratio of the front and rear wheels of the vehicle, the method further includes: Based on the fact that the vehicle is on a second type of surface with adhesion and the target control factor is 1, the correspondence between the vehicle speed and the ratio of the front and rear wheel angles is determined as the second control curve according to the front wheel steering angle and a two-dimensional lookup table.

7. The method according to claim 5 or 6, characterized in that, The step of determining the front-to-rear wheel angle ratio of the vehicle based on the target control factor and the vehicle speed, and based on the first control factor and the second control factor, includes: Based on the first control curve and the second control curve, determine the first control factor and the second control factor corresponding to the vehicle speed; Based on the first control factor and the second control factor, an estimation function is established between the target control factor and the angle ratio of the front and rear wheels; Based on the target control factor and the estimation function, the angle ratio of the front and rear wheels of the vehicle is determined.

8. The method according to claim 2, characterized in that, The method of controlling the vehicle steering based on the rear wheel target steering angle determined by the front and rear wheel angle ratio and the front wheel steering angle includes: The initial steering angle of the rear wheels is determined based on the front wheel steering angle, the vehicle speed, and a two-dimensional lookup table, and the angle ratio of the front and rear wheels. Based on the yaw rate and the vehicle speed, the initial steering angle of the rear wheels is corrected to obtain the target steering angle of the rear wheels; The vehicle is steered according to the target rear wheel steering angle.

9. A vehicle control device, characterized in that, A steering control unit applied to a vehicle, the device comprising: The acquisition module is used to acquire the adhesion coefficient between the wheels and the road surface, the vehicle speed, and the front wheel steering angle; A first processing module is configured to determine, based on the adhesion coefficient being within a threshold range, the larger of a first control factor and a second control factor as a target control factor; the first control factor is negatively correlated with the adhesion coefficient; the second control factor is positively correlated with the adhesion coefficient; wherein, before the adhesion coefficient reaches an intersection value, the target control factor is negatively correlated with the adhesion coefficient; after the adhesion coefficient reaches an intersection value, the target control factor is positively correlated with the adhesion coefficient. The second processing module is used to determine the front-to-rear wheel angle ratio of the vehicle based on the target control factor and the vehicle speed, and on the basis of the first control factor and the second control factor; the front-to-rear wheel angle ratio is an estimated value based on the first control factor and the second control factor, and the angle ratio corresponding to the vehicle speed when the estimated value is the target control factor; The control module is used to control the vehicle steering based on the rear wheel target steering angle determined by the front wheel angle ratio and the front wheel steering angle.

10. A vehicle, characterized in that, The vehicles include: Control unit; A memory storing computer-readable instructions that, when executed by the control unit, implement the method as described in any one of claims 1 to 8.

Images