A vehicle steering assist control method, system, device, and medium

Abstract

This application provides a vehicle steering assist control method, system, device, and medium. The method includes: acquiring vehicle driving data on the current road; determining the road surface adhesion coefficient based on the driving data; determining the front wheel superimposed torque and rear wheel steering angle based on the road surface adhesion coefficient and the driving data; determining the cooperative control torque based on the front wheel superimposed torque and rear wheel steering angle, and performing steering assist control on the vehicle. By calculating the front wheel superimposed torque and rear wheel steering angle adapted to different road conditions using the road surface adhesion coefficient, and performing cooperative control based on the front wheel superimposed torque and rear wheel steering angle, the overall handling stability and safety of the vehicle are ensured.

Description

Technical Field

[0001] This application relates to the field of vehicle steering control technology, and in particular to a vehicle steering assist control method, system, device and medium. Background Technology

[0002] With the development and popularization of automotive electrification and intelligent technologies, vehicle handling stability and safety have gradually become key factors in evaluating the driving experience. Currently, traditional methods typically improve vehicle handling stability and safety by providing electric power assistance or controlling the wheel steering ratio.

[0003] However, using a single front-wheel steering control or a simple rear-wheel steering control makes it difficult to simultaneously ensure vehicle handling stability and safety under various complex road conditions. Summary of the Invention

[0004] The purpose of this application is to provide a vehicle steering assist control method, system, electronic device, and storage medium that can solve the problem that the prior art is unable to simultaneously ensure the vehicle's handling stability and safety under various complex road conditions.

[0005] In a first aspect, embodiments of this application provide a vehicle steering assist control method, the method comprising:

[0006] Obtain vehicle driving data on the current road;

[0007] The road surface adhesion coefficient of the current road is determined based on the driving data;

[0008] The front wheel superimposed torque and rear wheel steering angle of the vehicle are determined based on the road surface adhesion coefficient and the driving data. Wherein, when the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, the rear wheel steering angle is calculated based on the yaw rate tracking term, the center of gravity sideslip angle stability term and the compensation angle. The compensation angle is used to counteract the yaw moment caused by the difference in adhesion on both sides of the current road.

[0009] The coordinated control torque is determined based on the superimposed torque of the front wheels and the steering angle of the rear wheels;

[0010] The vehicle is subjected to steering assist control based on the rear wheel angle and the coordinated control torque.

[0011] Optionally, determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the road surface adhesion coefficient and the driving data includes:

[0012] The corresponding steering assist control strategy is determined based on the road surface adhesion coefficient.

[0013] The front wheel superimposed torque and rear wheel steering angle of the vehicle are determined based on the steering assist control strategy and the driving data.

[0014] Optionally, the steering assist control strategy includes: a high-adhesion conventional mode control strategy, a low-adhesion stable mode control strategy, and a split-road mode control strategy.

[0015] The step of determining the corresponding steering assist control strategy based on the road surface adhesion coefficient includes:

[0016] When the road surface adhesion coefficient is greater than the first adhesion coefficient threshold, a high adhesion conventional mode control strategy is obtained; the high adhesion conventional mode takes vehicle stability as the control objective and sets a first feedforward gain function, a first angular velocity weight and a first centroid weight, wherein the first angular velocity weight is greater than the first centroid weight.

[0017] When the road surface adhesion coefficient is less than or equal to the first adhesion coefficient threshold, a low adhesion stability mode control strategy is obtained; the low adhesion stability mode control strategy takes vehicle agility as the control target, and sets a second feedforward gain function, a second angular velocity weight and a second centroid weight, wherein the second angular velocity weight is less than the second centroid weight.

[0018] When the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, a split road surface mode control strategy is obtained. The split road surface mode control strategy aims to maintain straight-line driving stability, sets a third feedforward gain function, a third angular velocity weight, and a third centroid weight, and determines a compensation angle based on the road surface adhesion coefficient. The compensation angle is used to offset the yaw moment caused by the different adhesion forces on both sides of the road.

[0019] Optionally, determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the steering assist control strategy and the driving data includes:

[0020] The vehicle's feedback torque and risk level are determined based on the driving data.

[0021] The feedforward torque and the rear wheel angle under the steering assist control strategy are calculated based on the feedforward gain function and weights included in the steering assist control strategy.

[0022] The corrective torque of the vehicle is determined based on the risk level.

[0023] The front wheel superimposed torque is determined based on the feedback torque, the feedforward torque, and the correction torque.

[0024] Optionally, calculating the feedforward torque and the rear wheel angle under the steering assist control strategy based on the feedforward gain function and weights included in the steering assist control strategy includes:

[0025] Under the high-adhesion conventional mode control strategy, the first feedforward gain function, the first angular velocity weight, and the first center of mass weight are matched; the feedforward torque is calculated based on the first feedforward gain function; and the rear wheel steering angle is calculated based on the driving data, the first angular velocity weight, and the first center of mass weight.

[0026] Under the low-adhesion stability mode control strategy, the second feedforward gain function, the second angular velocity weight, and the second center of gravity weight are matched and obtained; the feedforward torque is calculated based on the second feedforward gain function; and the rear wheel steering angle is calculated based on the driving data, the second angular velocity weight, and the second center of gravity weight.

[0027] Under the aforementioned split-road mode control strategy, the third feedforward gain function, the third angular velocity weight, and the third centroid weight are matched and obtained, and the compensation angle and compensation torque are determined based on the road adhesion coefficient; the feedforward torque is calculated based on the third feedforward gain function and the compensation torque; and the rear wheel steering angle is calculated based on the driving data, the third angular velocity weight, the third centroid weight, and the compensation angle.

[0028] Optionally, determining the coordinated control torque based on the superimposed torque of the front wheels and the steering angle of the rear wheels includes:

[0029] Predict the additional yaw moment required to maintain vehicle stability based on the driving data and the road surface adhesion coefficient.

[0030] The required coordinated control torque for each wheel of the vehicle is determined based on the additional yaw moment, the superimposed torque of the front wheels, and the steering angle of the rear wheels.

[0031] Optionally, determining the required coordinated control torque for each wheel of the vehicle based on the additional yaw moment, the front wheel superimposed torque, and the rear wheel steering angle includes:

[0032] The yaw moment contribution value is determined based on the superimposed torque of the front wheels and the steering angle of the rear wheels;

[0033] The compensation yaw moment is determined based on the difference between the additional yaw moment and the contribution value of the yaw moment;

[0034] The required coordinated control torque for each wheel is matched according to the compensated yaw moment and the preset distribution strategy.

[0035] Secondly, embodiments of this application provide a vehicle steering assist control system, the system comprising:

[0036] The data acquisition module is used to acquire vehicle driving data on the current road.

[0037] The road surface adhesion coefficient determination module is used to determine the road surface adhesion coefficient of the current road based on the driving data.

[0038] The first data processing module is used to determine the superimposed torque of the front wheels and the rear wheel steering angle of the vehicle based on the road surface adhesion coefficient and the driving data. Wherein, when the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, the rear wheel steering angle is calculated based on the yaw rate tracking term, the center of gravity sideslip angle stability term and the compensation angle. The compensation angle is used to offset the yaw torque caused by the difference in adhesion on both sides of the current road.

[0039] The second data processing module is used to determine the coordinated control torque based on the superimposed torque of the front wheels and the steering angle of the rear wheels;

[0040] A control module is used to perform steering assist control on the vehicle based on the rear wheel angle and the cooperative control torque.

[0041] Thirdly, embodiments of this application provide an electronic device, including: a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the method described above.

[0042] Fourthly, embodiments of this application provide a computer-readable storage medium on which a computer program is stored, which, when executed by a processor, implements the method described above.

[0043] Compared with the prior art, the embodiments of this application have the following advantages:

[0044] In this embodiment, the vehicle steering assist control method includes: acquiring vehicle driving data on the current road; determining the road surface adhesion coefficient based on the driving data; determining the front wheel superimposed torque and rear wheel steering angle based on the road surface adhesion coefficient and the driving data; determining the cooperative control torque based on the front wheel superimposed torque and rear wheel steering angle, and performing steering assist control on the vehicle. By calculating the front wheel superimposed torque and rear wheel steering angle adapted to different road conditions using the road surface adhesion coefficient, and performing cooperative control based on the front wheel superimposed torque and rear wheel steering angle, the overall handling stability and safety of the vehicle are ensured. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart illustrating the steps of a vehicle steering assist control method provided in an embodiment of this application;

[0047] Figure 2 This is a schematic diagram of the structure of a vehicle steering assist control system provided in an embodiment of this application;

[0048] Figure 3 This is a schematic diagram of an electronic device provided in an embodiment of this application;

[0049] Figure 4 This is a schematic diagram of a computer-readable storage medium provided in an embodiment of this application. Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in this application, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0052] The following description, in conjunction with the accompanying drawings, details a vehicle steering assist control method, system, electronic device, and storage medium provided in this application through specific embodiments and application scenarios.

[0053] With the development and popularization of automotive electrification and intelligent technologies, vehicle handling stability and safety have gradually become key factors in evaluating the driving experience. Currently, traditional methods typically improve vehicle handling stability and safety by providing electric power assistance or controlling the wheel steering ratio.

[0054] However, traditional electric power steering systems primarily provide steering assistance, but they cannot effectively compensate for changes in vehicle posture caused by road disturbances under complex road conditions. Furthermore, existing rear-wheel steering systems often employ simple front-to-rear wheel angle ratio control or linear model-based control methods, resulting in significant performance degradation under extreme conditions where tire forces approach saturation. The front-wheel and rear-wheel steering systems often operate independently, lacking coordinated control, making it difficult to achieve optimal vehicle stability. For these reasons, vehicles are prone to instability and handling difficulties when encountering complex conditions such as partially snow-covered roads, flooded roads, rainy parking garages, ramps, muddy roads, and cornering.

[0055] Reference Figure 1 The diagram illustrates a flowchart of a vehicle steering assist control method provided in an embodiment of this application, which may specifically include the following:

[0056] Step S101: Obtain the vehicle's driving data on the current road;

[0057] In this embodiment, the vehicle's driving data on the current road is determined by receiving raw signals from the vehicle's CAN bus and direct sensors. The driving data includes at least: steering wheel angle. Speed yaw rate Lateral acceleration Longitudinal acceleration Wheel speed of each wheel Multi-dimensional driving data provides more comprehensive data support for subsequent collaborative control.

[0058] Step S102: Determine the road surface adhesion coefficient of the current road based on the driving data;

[0059] In this embodiment, due to factors such as weather and road surface conditions, the maximum adhesion between the tires and the road surface varies for different vehicle models and under different weather conditions. Therefore, this application calculates the road surface adhesion coefficient of the current road by combining multi-dimensional driving data with the vehicle's own tire parameters. In turn, the road surface adhesion coefficient can be used to distinguish different road conditions, providing a theoretical basis for calculating the corresponding front wheel superimposed torque and rear wheel steering angle for different road conditions.

[0060] In practical implementation, the road adhesion coefficient corresponding to each wheel can be determined based on the above driving data. In this embodiment, the road adhesion coefficient... It can be calculated using the following formula;

[0061]

[0062] in, The road surface adhesion coefficient; It is lateral acceleration; It is the acceleration due to gravity; This refers to the yaw rate; The steady-state yaw rate can be predicted based on existing two-degree-of-freedom linear vehicle models. It represents the deviation between the driver's intention and the actual yaw rate. For vehicle speed; Let be the wheel slip ratio, where is the wheel slip ratio. The calculation formula is: , The radius of the wheel's rolling motion. The speed of each wheel; These are the preset wheel calibration coefficients; This is the preset yaw angle calibration coefficient. It should be noted that other existing methods can also be used to calculate the road adhesion coefficient for each wheel. .

[0063] Optionally, in addition to calculating the road adhesion coefficient, this embodiment can also predict the vehicle's center of gravity sideslip angle using driving data. centroid side slip angle This can be predicted using existing extended Kalman filters (EKF) or dynamic model observers. The accuracy of subsequent front wheel superimposed torque and rear wheel steering angle can be further improved by using the center of gravity sideslip angle and road adhesion coefficient.

[0064] Step S103: Determine the superimposed torque of the front wheels and the steering angle of the vehicle based on the road surface adhesion coefficient and the driving data. Wherein, when the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, the steering angle of the rear wheels is calculated based on the yaw rate tracking term, the center of gravity sideslip angle stability term and the compensation angle. The compensation angle is used to offset the yaw moment caused by the difference in adhesion on both sides of the current road.

[0065] Since the maximum adhesion between the vehicle and the road surface varies under different road conditions, it is necessary to calculate the appropriate front wheel superimposed torque and rear wheel steering angle for different road conditions to ensure that the vehicle can maintain driving stability and safety under different road conditions and driving scenarios, such as semi-snowy roads, waterlogged roads, rainy parking lots, double ramps, muddy roads, and cornering.

[0066] Specifically, front wheel superimposed torque refers to the additional steering assist torque dynamically added to the traditional electric power steering system, enabling the driver to more precisely control the vehicle's steering under maximum adhesion on different road surfaces, avoiding steering lag or oversteering caused by insufficient assistance; rear wheel steering angle is the target steering angle that needs to be adjusted to optimize the vehicle's yaw response and lateral stability in scenarios such as cornering under different road conditions.

[0067] This embodiment distinguishes different road conditions by using the road surface adhesion coefficient. Different steering assist control strategies are adopted for different road conditions to calculate the optimal front wheel superimposed torque and rear wheel steering angle under the road conditions. Based on the road surface adhesion coefficient, the adaptive control strategy enables the vehicle to achieve stable steering under different conditions such as semi-snowy roads, rainy parking lots, and muddy roads, which significantly improves driving safety and driving experience.

[0068] Step S104: Determine the cooperative control torque based on the superimposed torque of the front wheels and the steering angle of the rear wheels;

[0069] After calculating the superimposed torque of the front wheels and the steering angle of the rear wheels, since the steering of the rear wheels will change the tire force distribution, in order to adapt to the scenario after the change in tire force distribution, the optimal collaborative control torque will be calculated based on the change in tire force distribution, when the superimposed torque of the front wheels and the steering angle of the rear wheels are calculated.

[0070] Step 105: Perform steering assist control on the vehicle based on the rear wheel angle and the cooperative control torque.

[0071] Traditional front-wheel steering and rear-wheel steering systems often operate independently, lacking coordinated control. Rear-wheel steering alters tire force distribution, causing the control parameters obtained from existing independent mechanisms to be inadequate for adapting to the changed tire force distribution. This results in overall vehicle stability instability and insufficient safety. This embodiment, after obtaining the superimposed torque of the front wheels and the steering angle of the rear wheels, performs steering assistance control on the vehicle based on coordinated control torque, achieving vehicle-wide stability control.

[0072] In this embodiment, the vehicle steering assist control method includes: acquiring vehicle driving data on the current road; determining the road surface adhesion coefficient based on the driving data; determining the front wheel superimposed torque and rear wheel steering angle based on the road surface adhesion coefficient and the driving data; determining the cooperative control torque based on the front wheel superimposed torque and rear wheel steering angle, and performing steering assist control on the vehicle. By calculating the front wheel superimposed torque and rear wheel steering angle adapted to different road conditions using the road surface adhesion coefficient, and performing cooperative control based on the front wheel superimposed torque and rear wheel steering angle, the overall handling stability and safety of the vehicle are ensured.

[0073] In one embodiment of this application, determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the road surface adhesion coefficient and the driving data includes:

[0074] The corresponding steering assist control strategy is determined based on the road surface adhesion coefficient.

[0075] The front wheel superimposed torque and rear wheel steering angle of the vehicle are determined based on the steering assist control strategy and the driving data.

[0076] The road surface adhesion coefficient characterizes the maximum adhesion between the vehicle and the road surface under different road conditions. Therefore, different steering assist control strategies need to be set for different road conditions to calculate the corresponding front wheel superimposed torque and rear wheel steering angle. This embodiment introduces the road surface adhesion coefficient as the basis for classifying different road conditions to adapt to different road conditions.

[0077] Based on the road surface adhesion coefficient, an adaptive steering assist control strategy is matched to the current road conditions. This steering assist control strategy is then used to calculate the superimposed torque of the front wheels and the steering angle of the rear wheels, thereby improving the vehicle's handling stability and safety under different road conditions such as semi-snowy roads and waterlogged roads.

[0078] In one embodiment of this application, the steering assist control strategy includes: a high-adhesion conventional mode control strategy, a low-adhesion stable mode control strategy, and a split-road mode control strategy;

[0079] The step of determining the corresponding steering assist control strategy based on the road surface adhesion coefficient includes:

[0080] When the road surface adhesion coefficient is greater than the first adhesion coefficient threshold, a high adhesion conventional mode control strategy is obtained; the high adhesion conventional mode takes vehicle stability as the control objective and sets a first feedforward gain function, a first angular velocity weight and a first centroid weight, wherein the first angular velocity weight is greater than the first centroid weight.

[0081] When the road surface adhesion coefficient is less than or equal to the first adhesion coefficient threshold, a low adhesion stability mode control strategy is obtained; the low adhesion stability mode control strategy takes vehicle agility as the control target, and sets a second feedforward gain function, a second angular velocity weight and a second centroid weight, wherein the second angular velocity weight is less than the second centroid weight.

[0082] When the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, a split road surface mode control strategy is obtained. The split road surface mode control strategy aims to maintain straight-line driving stability, sets a third feedforward gain function, a third angular velocity weight, and a third centroid weight, and determines a compensation angle based on the road surface adhesion coefficient. The compensation angle is used to offset the yaw moment caused by the different adhesion forces on both sides of the road.

[0083] In this embodiment, different steering assist control strategies are distinguished by the road surface adhesion coefficient, the first adhesion coefficient threshold, and the difference between the adhesion coefficients on the left and right sides of the road. The steering assist control strategies are divided into: high adhesion conventional mode control strategy, low adhesion stable mode control strategy, and split road surface mode control strategy.

[0084] Specifically, when the road surface adhesion coefficient is greater than the first adhesion coefficient threshold (e.g.: When it is predicted that the current road is a high-adhesion road, a high-adhesion conventional mode control strategy is matched to calculate the front wheel superimposed torque and rear wheel steering angle under the road condition. When it is a high-adhesion road, the high-adhesion conventional mode sets the first feedforward gain function, the first angular velocity weight and the first centroid weight with vehicle stability as the control target. Among them, the first angular velocity weight is greater than the first centroid weight.

[0085] When the road surface adhesion coefficient is less than or equal to the first adhesion coefficient threshold (e.g.: When the current road is predicted to be a low-adhesion road, a low-adhesion stability mode control strategy is matched to calculate the front wheel superimposed torque and rear wheel steering angle under the road condition. When the road is low-adhesion, the vehicle agility is the control target. The low-adhesion stability mode control strategy sets a second feedforward gain function, a second angular velocity weight and a second centroid weight, where the second angular velocity weight is less than the second centroid weight.

[0086] When there is road maintenance or different amounts of snow or water on both sides of the road, the road surface adhesion coefficient will be different. If the road surface adhesion coefficient is assumed to be the same on both sides of the road, the stability and safety of vehicle handling will be insufficient under road conditions such as road maintenance or different amounts of snow or water on both sides of the road, which may lead to risks such as slippage and loss of control.

[0087] Therefore, this application predicts the road surface adhesion coefficient on the left and right sides of the current road based on the wheel speed and acceleration of the left and right tires of the vehicle. When the difference between the road surface adhesion coefficient on the left and right sides of the current road is greater than the second adhesion coefficient threshold, it predicts that the current road is a split road surface. A split road surface mode control strategy is matched to calculate the front wheel superimposed torque and rear wheel steering angle under this road condition. When on a split road surface, the control objective is to maintain straight driving stability. The split road surface mode control strategy sets a third feedforward gain function, a third angular velocity weight, and a third centroid weight, and determines a compensation steering angle based on the road surface adhesion coefficient. The compensation steering angle is used to offset the yaw moment caused by the different adhesion forces on both sides of the road.

[0088] This embodiment divides the steering assist control strategy into a high-adhesion normal mode, a low-adhesion stable mode, and a split-road mode. Based on a comparison of the road surface adhesion coefficient with a first threshold and a judgment of the difference in adhesion coefficients between the left and right sides of the road with a second threshold, it accurately distinguishes road conditions. This strategy effectively solves the defect of traditional systems that assume the road surface adhesion coefficients are the same on both sides of the road. Especially in road maintenance, uneven snow / water accumulation, or split-road conditions, it avoids vehicle instability caused by differences in road surface adhesion coefficients. By dynamically matching the front wheel superimposed torque and the rear wheel steering angle calculation strategy, it significantly improves the vehicle's steering stability on complex road surfaces, eliminates the risk of slippage and loss of control, and ensures driving safety and handling reliability.

[0089] In this embodiment of the application, determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the steering assist control strategy and the driving data includes:

[0090] The vehicle's feedback torque and risk level are determined based on the driving data.

[0091] The feedforward torque and the rear wheel angle under the steering assist control strategy are calculated based on the feedforward gain function and weights included in the steering assist control strategy.

[0092] The corrective torque of the vehicle is determined based on the risk level.

[0093] The front wheel superimposed torque is determined based on the feedback torque, the feedforward torque, and the correction torque.

[0094] In this embodiment, regardless of whether it is the high-adhesion conventional mode control strategy, the low-adhesion stable mode control strategy, or the split-road mode control strategy, it is necessary to predict the desired yaw rate based on the current road driving data. Desired yaw rate The calculation process is as follows:

[0095] First, the steady-state yaw rate can be predicted based on the existing two-degree-of-freedom linear vehicle model. .

[0096] Secondly, based on the road surface adhesion coefficient and gravitational acceleration speed Calculate the dynamic saturation limit of the desired yaw rate. This value is based on the road surface adhesion coefficient. Therefore, the calculation is essentially a value based on physical limits, and thus it is used as a safety boundary, the expected dynamic saturation limit of the yaw rate. The calculation formula is as follows:

[0097]

[0098] in, The dynamic saturation limit for the desired yaw rate; Let be the road surface adhesion coefficient, where, under the split road surface mode control strategy, the road surface adhesion coefficient is... It is the minimum road surface adhesion coefficient between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road. It is the acceleration due to gravity; The speed is the vehicle speed.

[0099] Then, based on the steady-state yaw rate Dynamic saturation limit of desired yaw rate The minimum value in the range determines the final desired yaw rate. Desired yaw rate The calculation formula is as follows:

[0100]

[0101] in, The desired yaw rate; This represents the steady-state yaw rate. The dynamic saturation limit for the desired yaw rate; It is a symbolic function.

[0102] In this embodiment, the sideslip angle of the center of gravity is calculated based on the driving data. Dynamic saturation limit of yaw rate To determine the current risk level of the vehicle;

[0103] Specifically, the risk level is determined by assessing the following four risk events:

[0104] Risk event C1: Exceeding the limit of the centroid side slip angle

[0105] Side slip angle at the center of mass When the absolute value of the side slip angle exceeds the side slip angle threshold, the vehicle is considered to have entered an unstable linear region, posing a risk of exceeding the center of gravity side slip angle limit.

[0106] Risk event C2: Exceeding the limit of the rate of change of the centroid sideslip angle.

[0107] Rate of change of centroid side slip angle Used to detect sudden vehicle instability trends (such as rapid fishtailing), the rate of change of the sideslip angle at the center of gravity. When the rate of change exceeds the threshold, the vehicle is considered to have a tendency to become unstable, and there is a risk of the rate of change of the center of gravity sideslip angle exceeding the limit.

[0108] Risk event C3: Mismatch between driver operation and vehicle response

[0109] At the steering wheel angle greater than the steering wheel angle threshold, yaw rate Less than And lateral acceleration Approaching the current road surface adhesion limit (i.e., When the driver makes a sudden steering input, there is a risk that the vehicle's actual yaw response is severely delayed, and the lateral acceleration is close to the current road surface adhesion limit. This indicates a risk of mismatch between driver operation and vehicle response. This is the preset mapping ratio coefficient between the steering wheel angle and the yaw rate.

[0110] Risk event C4: Severe overshoot of yaw rate

[0111] When the yaw rate significantly exceeds the dynamic safety boundary determined by road surface adhesion (i.e., When the yaw rate is 0, it indicates that the vehicle is in an unstable state of oversteering and there is a risk of severe overshoot in the yaw rate.

[0112] In the specific implementation, corresponding risk values ​​(1-10 points) are pre-set for risk events C1, C2, C3, and C4. When risk event C1 exists, risk value X1 is recorded; when risk event C2 exists, risk value X2 is recorded; when risk event C3 exists, risk value X3 is recorded; and when risk event C4 exists, risk value X4 is recorded. Then, the average value is calculated based on the recorded risk values. ,Will As a comprehensive risk score.

[0113] Map the overall risk score to a risk weight between 0 and 1. , with the initial corrective torque Multiplying these together yields the correcting torque.

[0114] This application dynamically calculates the comprehensive risk score of the current working condition by using the steering wheel angular velocity and yaw rate, and determines the corrective torque based on the comprehensive risk score, which can effectively suppress steering instability caused by driver misoperation.

[0115] Optionally, different sideslip angle thresholds and steering wheel angle thresholds can be set for different steering assist control strategies;

[0116] Specifically, considering that low-adhesion roads are prone to sideslip, the low-adhesion stability mode control strategy aims to improve stability. Based on this, the steering wheel angle threshold set in the low-adhesion stability mode control strategy is lower than the steering wheel angle threshold set in the high-adhesion conventional mode control strategy; the sideslip angle threshold set in the low-adhesion stability mode control strategy is also lower than the sideslip angle threshold set in the high-adhesion conventional mode control strategy, making the detection of misoperation more sensitive.

[0117] In addition, this embodiment can also determine the vehicle's feedback torque based on driving data; then calculate the feedforward torque and the rear wheel angle under the steering assist control strategy based on the feedforward gain function and weights included in the steering assist control strategy; finally, determine the front wheel superimposed torque based on the feedback torque, feedforward torque and correction torque.

[0118] In other words, the formula for calculating the superimposed torque of the front wheels is shown in Formula 1 below:

[0119] Formula 1:

[0120]

[0121] in, Add torque to the front wheels; The feedforward torque is calculated using different steering assist control strategies; Risk weights; This is the initial correction torque.

[0122] Optionally, the initial corrective torque It can also be calculated using the following formula:

[0123]

[0124] in, This is the initial corrective torque; The preset centroid sideslip angle ratio gain characterizes the correction strength for the current centroid sideslip angle. It is the centroid sideslip angle; The preset differential gain of the centroid sideslip angle represents the strength of the correction to the rate of change of the centroid sideslip angle; t is the time variable.

[0125] In practice, to calculate the superimposed torque on the front wheels, it is necessary to first determine the vehicle's feedback torque based on driving data. Feedback torque is used to eliminate steady-state errors and suppress disturbances. The calculation formula is shown in Formula 2 below:

[0126] Formula 2:

[0127]

[0128] in, For feedback torque; The desired yaw rate; This refers to the yaw rate; The preset adaptive proportional gain characterizes the response to yaw rate deviation. The immediate reaction intensity; The preset adaptive integral gain characterizes the historical cumulative value of the yaw rate deviation. The reaction intensity is used to eliminate steady-state deviations caused by system nonlinearity, parameter drift, etc. The preset adaptive differential gain characterizes the prediction and damping effect of the rate of change of yaw rate deviation, and is used to increase system damping, suppress overshoot, and improve stability.

[0129] Since the high-adhesion conventional mode control strategy, the low-adhesion stable mode control strategy, and the split-road mode control strategy are designed for different road conditions and have different adjustment directions, this embodiment sets different feedforward gain functions, different correction thresholds, and different weights for different control strategies to adapt to different road conditions.

[0130] In this embodiment of the application, the step of calculating the feedforward torque and the rear wheel angle under the steering assist control strategy based on the feedforward gain function and weights included in the steering assist control strategy includes:

[0131] Under the high-adhesion conventional mode control strategy, the first feedforward gain function, the first angular velocity weight, and the first center of mass weight are matched; the feedforward torque is calculated based on the first feedforward gain function; and the rear wheel steering angle is calculated based on the driving data, the first angular velocity weight, and the first center of mass weight.

[0132] Under the low-adhesion stability mode control strategy, the second feedforward gain function, the second angular velocity weight, and the second center of gravity weight are matched to obtain the second feedforward gain function; the feedforward torque is calculated based on the second feedforward gain function; and the rear wheel steering angle is calculated based on the driving data, the second angular velocity weight, and the second center of gravity weight.

[0133] Under the aforementioned split-road mode control strategy, the third feedforward gain function, the third angular velocity weight, and the third centroid weight are matched and obtained, and the compensation angle and compensation torque are determined based on the road adhesion coefficient; the feedforward torque is calculated based on the third feedforward gain function and the compensation torque; and the rear wheel steering angle is calculated based on the driving data, the third angular velocity weight, the third centroid weight, and the compensation angle.

[0134] In this embodiment, for the high-attachment conventional mode control strategy, the first feedforward gain function is obtained by matching. The first angular velocity weight and the first centroid weight; wherein, the first feedforward gain function It has been tuned to provide a light, linear assist.

[0135] In calculating the superimposed torque of the front wheels, the first step is based on the first feedforward gain function. The first feedforward torque is calculated using the following formula three based on the driving data. :

[0136] Formula 3:

[0137]

[0138] in, This is the first feedforward torque; The first feedforward gain function can be obtained from the feedforward gain model pre-trained based on historical data, and the feedforward gain function corresponding to different steering assist control strategies can be obtained from the feedforward gain model. Let be the desired yaw rate.

[0139] In this embodiment, under the high-attachment conventional mode control strategy, the first feedforward gain function is determined from the feedforward gain model. It can be represented as follows:

[0140]

[0141] in, The preset high adhesion reference gain; This is the preset reference speed; For vehicle speed; This is the preset minimum vehicle speed constant; Based on road surface adhesion coefficient The set road adhesion coefficient correction factor is used in the high adhesion conventional mode control strategy. When this is the case, you can set this mode. This is a preset constant value, such as 1.

[0142] Then the first feedforward torque Substituting into Formula 1, the superimposed torque of the front wheels under the high adhesion stability mode control strategy is obtained;

[0143] In this embodiment, the rear wheel steering angle is divided into a yaw rate tracking term. And the stability term of the centroid side slip angle Tracking terms via yaw rate Stability term of center of mass side slip angle The rear wheel steering angle is obtained by weighting the first angular velocity and the first center of mass, respectively. Rear wheel steering angle The calculation formula is shown in Formula 4 below:

[0144] Formula 4:

[0145]

[0146] in, The rear wheel steering angle; For yaw rate tracking; The first angular velocity weight; This is the stability term for the centroid sideslip angle; The first centroid weight; and All values ​​are preset. Under the high-adhesion normal mode control strategy, the goal is to improve agility, optimize steering feel, and ensure basic stability. Therefore, these settings are... weight Greater than weight .

[0147] Yaw rate tracking item To enhance yaw response speed, it is calculated using the following formula five:

[0148] Formula 5:

[0149]

[0150]

[0151] in, For yaw rate tracking; This is the first rear wheel steering yaw control gain function. The yaw rate deviation is mapped to a yaw rate tracking term using this function, and its value is determined by the input variable vehicle speed. and road surface adhesion coefficient Together, the value of this function determines the force and phase of the rear-wheel steering system when compensating for yaw rate deviations, under the high-adhesion conventional mode control strategy. It is configured to operate at low to medium speeds (i.e., When the front wheels turn, a steering angle opposite to the front wheel steering angle is generated (reducing the turning radius), at high speeds (i.e., When this occurs, a small rotation angle in the same direction is generated (improving yaw response speed and stability); This refers to the deviation in yaw rate. The first preset reference gain; The preset first reference adhesion coefficient; This is the preset reference speed; This is the preset minimum vehicle speed constant; For phase switching vehicle speed threshold, via It can achieve phase switching between low and medium speeds in opposite directions and high speeds in the same direction, and the amplitude is naturally adjusted with vehicle speed and road surface adhesion coefficient. This is the transition bandwidth coefficient.

[0152] Center of mass sideslip angle stability term To suppress excessive sideslip angles and improve stability, it is calculated using the following formula six:

[0153] Formula Six:

[0154]

[0155] in, This is the stability term for the centroid sideslip angle; The gain function for controlling the sideslip of the first rear wheel steering center of gravity can be determined based on vehicle speed. and road surface adhesion coefficient The corresponding function value is obtained by looking up the table, and the center of gravity sideslip angle is mapped to the yaw rate tracking term by the first rear wheel steering center of gravity sideslip control gain function. It is the centroid sideslip angle.

[0156] This embodiment achieves light linear power assist through a first feedforward gain function in high-adhesion normal mode. The rear wheel steering angle adopts a weighted strategy where the weight of the yaw rate tracking term is greater than the weight of the center of gravity sideslip angle stability term, accurately balancing steering agility and stability, optimizing steering response characteristics under high-adhesion road conditions, improving handling precision and driving safety, and avoiding the response lag problem of traditional systems during sharp turns.

[0157] For the low-attachment stable mode control strategy, the second angular velocity weight and the second centroid weight are obtained by matching, and the second feedforward gain function is determined from the pre-trained feedforward gain model. ; where the second feedforward gain function Reassigned as The steering angle is lowered and increased, actively increasing the steering feel to prevent the driver from easily inputting too large a steering angle;

[0158] In calculating the superimposed torque of the front wheels, the calculation is first based on the second feedforward gain function. The second feedforward torque is calculated using the following formula (Formula 7) based on the driving data. :

[0159] Formula 7:

[0160]

[0161] in, This is the second feedforward torque; This is the second feedforward gain function; Let be the desired yaw rate.

[0162] In this embodiment, under the low-attachment stable mode control strategy, the second feedforward gain function is determined from the feedforward gain model. It can be represented as follows:

[0163]

[0164] in, The preset low-adhesion reference gain; This is the preset reference speed; For vehicle speed; This is the preset minimum vehicle speed constant; As a road surface adhesion coefficient correction factor, in the low adhesion conventional mode control strategy ( When ), you can set for ;in, The preset first reference adhesion coefficient, for example: ; For example, the preset stability term control coefficient: .

[0165] Then the second feedforward torque Substituting into Formula 1, the superimposed torque of the front wheels under the low-adhesion stability mode control strategy is calculated.

[0166] For the calculation of the rear wheel steering angle under the low-adhesion stability mode control strategy, the rear wheel steering angle under this road condition is calculated according to the following formula:

[0167] Formula 8:

[0168]

[0169] in, The rear wheel steering angle; For yaw rate tracking; The weight is the second angular velocity. This is the stability term for the centroid sideslip angle; The second centroid weight; and All values ​​are preset. Under the low-adhesion stable mode control strategy, stability is the control objective, therefore these values ​​are set. Less than .

[0170] Yaw rate tracking item To enhance yaw response speed, it is calculated using the following formula (nine):

[0171] Formula Nine:

[0172]

[0173]

[0174] in, For yaw rate tracking; The second rear wheel steering yaw control gain function maps the yaw rate deviation to a yaw rate tracking term. Greater than the first rear wheel steering yaw control gain function ; This refers to the deviation in yaw rate. The second preset reference gain; This is the preset second reference adhesion coefficient; This is the preset reference speed; This is the preset minimum vehicle speed constant; The phase switching speed threshold is where, The function value is negative (phase switching term is canceled), ensuring that the rear wheels always move in the opposite direction to the front wheels; the amplitude varies with... It decreases and then increases.

[0175] Center of mass sideslip angle stability term To suppress excessive sideslip angles and improve stability, it is calculated using the following formula:

[0176] Formula 10:

[0177]

[0178]

[0179] in, This is the stability term for the centroid sideslip angle; The second rear wheel steering center of gravity sideslip control gain function maps the sideslip angle to a yaw rate tracking term. The minimum value is greater than the first rear wheel steering center of gravity sideslip control gain function. The maximum value; It is the centroid sideslip angle; This is the preset centroid gain coefficient; The preset stability term control coefficients are, where, The function value varies with The decrease and increase make the stability term of the centroid sideslip angle dominant, preferentially suppressing sideslip.

[0180] In this embodiment, under the low adhesion stability mode, the second feedforward gain function varies with the road adhesion coefficient. The steering feel is actively increased by reducing the steering input to suppress the driver's oversteer input; the rear wheel steering angle adopts a weighted strategy in which the weight of the second angular velocity is less than the weight of the second center of gravity, which strengthens the effect of the center of gravity sideslip angle stabilization term, significantly improves the steering stability on low-adhesion road surfaces (such as snow and water), effectively prevents the risk of sideslip and loss of control, and ensures driving safety under extreme conditions.

[0181] For the split-road control strategy, since the road surface adhesion coefficients on the left and right sides of the road are very different, the front and rear wheel control focuses on compensating for the yaw moment caused by the uneven adhesion on both sides.

[0182] The third angular velocity weight and the third centroid weight are obtained by matching under the split-road mode control strategy. The third feedforward gain function is determined from the pre-trained feedforward gain model. For special road conditions where there is a large difference in the road surface adhesion coefficient between the left and right sides, the compensation torque will be determined based on the road surface adhesion coefficient. To help the driver resist veering off course;

[0183] In calculating the superimposed torque of the front wheels, the calculation is first based on the third feedforward gain function. The third feedforward torque is calculated using the following formula eleven based on the driving data. :

[0184] Formula 11:

[0185]

[0186] in, This is the third feedforward torque; This is the third feedforward gain function; The desired yaw rate; To compensate for torque, a large model is pre-trained by collecting historical data, enabling the model to learn the appropriate compensation torque under different differences in road surface adhesion coefficients.

[0187] In this embodiment, the third feedforward gain function determined from the feedforward gain model is used in the open-path mode control strategy. It can be represented as follows:

[0188]

[0189] in, The preset reference gain for the split road surface; This is the preset reference speed; For vehicle speed; This is the preset minimum vehicle speed constant; The preset first reference adhesion coefficient; This represents the road surface adhesion coefficient on the left side of the current road. This represents the road surface adhesion coefficient on the right side of the current road. It is the minimum value between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road; The preset asymmetric gain coefficient; It is a symbolic function; This refers to the steering wheel angle.

[0190] Specifically, the compensation torque is determined based on the difference in adhesion coefficients of different road surfaces. The formula is as follows:

[0191]

[0192] in, To compensate for the torque coefficient; This represents the road surface adhesion coefficient on the left side of the current road. This represents the road surface adhesion coefficient on the right side of the current road. It is a symbolic function; Steering wheel angle; For vehicle speed; The preset compensation item is based on the vehicle speed. This is the preset minimum vehicle speed constant for the compensation term.

[0193] Then the third feedforward torque Substituting into Formula 1, the superimposed torque of the front wheels under the split-road mode control strategy is calculated;

[0194] For the calculation of the rear wheel steering angle under the split-road mode control strategy, in addition to calculating the yaw rate tracking term... And the stability term of the centroid side slip angle Angle compensation was introduced. This generates a yaw moment to counteract the deviation and balance the instability caused by the difference in adhesion between the left and right sides of the road.

[0195] Specifically, compensation corner Based on the estimated difference between the left longitudinal force and the right longitudinal force The calculation is then performed using the following formula (twelve) to calculate the rear wheel steering angle under this road condition:

[0196] Formula 12:

[0197]

[0198] in, The rear wheel steering angle; For yaw rate tracking; Weight for the third angular velocity; This is the stability term for the centroid sideslip angle. , and The unit is rad; The third centroid weight; and All are preset values.

[0199] Yaw rate tracking item To enhance yaw response speed, it is calculated using the following formula (xiii):

[0200] Formula Thirteen:

[0201]

[0202]

[0203] in, For yaw rate tracking; The third rear wheel steering yaw control gain function maps the yaw rate deviation to a yaw rate tracking term through the third rear wheel steering yaw control gain function. This refers to the deviation in yaw rate. The second preset reference gain; This is the preset second reference adhesion coefficient; This is the preset reference speed; This is the preset minimum vehicle speed constant; The phase switching speed threshold is where, The function value is negative (phase switching term is canceled), ensuring that the rear wheels always move in the opposite direction to the front wheels; the amplitude varies with... Decrease and increase; for example, the second preset reference gain. The unit can be seconds (s), and the third rear wheel steering yaw control gain function. The unit can be seconds (s); yaw rate deviation The unit is rad / s; yaw rate tracking item The unit is rad.

[0204] Center of mass sideslip angle stability term To suppress excessive sideslip angles and improve stability, it is calculated using the following formula fourteen:

[0205] Formula Fourteen:

[0206]

[0207]

[0208] in, This is the stability term for the centroid sideslip angle; The third rear wheel steering center of gravity sideslip control gain function maps the center of gravity sideslip angle into a yaw rate tracking term through the third rear wheel steering center of gravity sideslip control gain function. It is the centroid sideslip angle; This is the preset centroid gain coefficient; The preset stability term control coefficients are, where, The function value varies with The decrease and increase make the stability term of the centroid sideslip angle dominant, preferentially suppressing sideslip.

[0209] In this embodiment, under the split-road mode, the third feedforward gain function and the compensation torque are used. Actively compensates for yaw moment to prevent vehicle deviation caused by differences in road surface adhesion coefficient. Rear wheel steering angle compensation is introduced. Based on the difference between the longitudinal force on the left and the longitudinal force on the right Real-time calculations generate counteracting torques to balance lateral instability. This strategy precisely addresses uneven adhesion in conditions such as road maintenance and partial snow accumulation on opposing surfaces, significantly improving lateral control accuracy, effectively suppressing the risk of sideslip and loss of control, and ensuring stable and safe vehicle operation under complex road conditions.

[0210] In one embodiment of this application, determining the cooperative control torque based on the superimposed torque of the front wheels and the steering angle of the rear wheels includes:

[0211] Predict the additional yaw moment required to maintain vehicle stability based on the driving data and the road surface adhesion coefficient.

[0212] The required coordinated control torque for each wheel of the vehicle is determined based on the additional yaw moment, the superimposed torque of the front wheels, and the steering angle of the rear wheels;

[0213] The vehicle is assisted in steering control by means of the rear wheel angle and the coordinated control torque.

[0214] Since rear-wheel steering changes the tire force distribution, in order to adapt to the scenario after the tire force distribution changes, this embodiment, after obtaining the front wheel superimposed torque and the rear wheel steering angle, will collaboratively calculate the optimal collaborative control torque based on the change in tire force distribution, and perform steering assistance control on the vehicle based on the collaborative control torque to achieve vehicle-level stability control.

[0215] Specifically, it can be based on the rear wheel steering angle. yaw rate deviation and centroid side slip angle Design a PID controller to calculate the rear wheel steering angle δ_r based on the current road conditions and the calculated yaw rate deviation from the driving data. and centroid side slip angle The additional yaw moment is predicted by the PID controller. ; then will The torque is distributed to specific wheels of the vehicle (e.g., left front wheel, right front wheel, left rear wheel, right rear wheel) to obtain the distributed torque for each wheel. Finally, a cooperative control torque is generated based on the difference between the superimposed torque of the front wheels and the distributed torque of the front wheels of the vehicle. The steering assist control of the vehicle is performed through the rear wheel steering angle and the cooperative control torque.

[0216] After obtaining the superimposed torque of the front wheels and the steering angle of the rear wheels, this application calculates the additional yaw moment based on the change in tire force distribution using a PID controller. This torque is then distributed to each wheel, generating a coordinated control torque. This torque works in conjunction with the superimposed torque of the front wheels to compensate for uneven tire force distribution caused by rear-wheel steering in real time, optimizing the vehicle's yaw dynamics. This effectively suppresses the risk of sideslip and loss of control during steering, significantly improving the overall stability of the vehicle under dynamic conditions, achieving deep coordination between front and rear wheel control, and ensuring driving safety under extreme road conditions.

[0217] In one embodiment of this application, determining the required coordinated control torque for each wheel of the vehicle based on the additional yaw moment, the front wheel superimposed torque, and the rear wheel steering angle includes:

[0218] The yaw moment contribution value is determined based on the superimposed torque of the front wheels and the steering angle of the rear wheels;

[0219] The compensation yaw moment is determined based on the difference between the additional yaw moment and the contribution value of the yaw moment;

[0220] The required coordinated control torque for each wheel is matched according to the compensated yaw moment and the preset distribution strategy.

[0221] Specifically, determining the required coordinated control torque for each wheel of the vehicle includes the following steps:

[0222] Step 1: Determine the desired additional yaw moment

[0223] Based on the current vehicle state (such as yaw rate deviation and sideslip angle) and the difference in left and right road adhesion, a closed-loop control algorithm with feedforward is used to calculate the additional yaw moment required to maintain or restore vehicle stability. This moment reflects the additional rotational force that the system should apply to the vehicle about its vertical axis of gravity, and its direction depends on the need to resist vehicle deviation or oversteering.

[0224] Step 2: Estimate the sum of the front wheel superimposed torque and the yaw moment contributed by the rear wheel steering angle.

[0225] The superimposed torque on the front wheels acts on the front wheels through the steering system, changing the lateral force of the front wheels and thus generating a portion of the yaw moment; the steering angle of the rear wheels directly changes the lateral force of the rear wheels, also contributing to the yaw moment.

[0226] In this embodiment, the longitudinal forces of the left and right front wheels after the front wheel superimposed torque is executed by the EPS motor are predicted. Then, based on the existing Direct Yaw Moment Control (DYC) method, the yaw moment contributed by the front wheel superimposed torque is calculated based on the difference between the longitudinal forces of the right and left front wheels.

[0227] Next, based on the predicted rear wheel steering angle and the rear wheel slip angle after vehicle control, the corresponding rear wheel lateral force is calculated using tire dynamics characteristics. ,in, This refers to the lateral force on the rear wheel; Rear wheel lateral stiffness; This refers to the rear wheel slip angle;

[0228] Then, the yaw moment contributed by the rear wheel steering angle is determined based on the difference between the lateral force of the front wheel and the lateral force of the rear wheel.

[0229] By summing the yaw moment contributed by the front wheel superimposed torque and the yaw moment contributed by the rear wheel steering angle, the sum of the contributed yaw moments is predicted. These predicted yaw moment contribution values ​​reflect the amount of stability compensation actively provided by the front and rear wheel steering systems at the current moment of control.

[0230] Step 3: Calculate the yaw moment that needs to be supplemented by the braking / drive system.

[0231] Subtracting the sum of the yaw moments already contributed by the front and rear wheels from the desired additional yaw moment yields the difference in yaw moment that the braking / drive system needs to provide. If this difference is close to zero, no intervention from the braking / drive system is required; if the difference is positive or negative, it indicates that the existing steering compensation is insufficient or excessive, and precise supplementation with yaw moment of corresponding direction and magnitude is required through differential braking or torque vector control.

[0232] Step 4: Distribute the yaw moment difference to each wheel to form a superimposed torque command.

[0233] In practice, the direction of the required yaw moment needs to be determined based on the sign of the yaw moment difference. If the yaw moment difference is positive, it means that a clockwise yaw moment is needed to resist the leftward deviation. If the yaw moment difference is negative, it means that a counterclockwise yaw moment is needed to resist the rightward deviation.

[0234] Subsequently, the yaw moment difference is distributed to each wheel to form a superimposed torque command. In this embodiment, a single-wheel braking strategy can be prioritized. When clockwise yaw moment is needed, braking force is applied to the right wheel to obtain a rapid response; when counterclockwise yaw moment is needed, braking force is applied to the left wheel. To ensure that the generated yaw moment can quickly and accurately match the requirements, the correspondence between the yaw moment difference and the braking force required by the wheel can be recorded through real vehicle testing under typical operating conditions (different vehicle speeds and adhesion coefficients), establishing a two-dimensional mapping table. During the control process, the current yaw moment difference is obtained, and the required braking force of the corresponding wheel is determined by looking up the table. Based on the required braking force of the wheel, a torque adjustment command is generated.

[0235] If the braking force required for a single wheel exceeds the current road surface adhesion limit of that wheel, a multi-wheel distribution strategy is activated: braking force is applied simultaneously to the front and rear wheels on the same side, and distributed according to the vertical load ratio of each wheel.

[0236] Ultimately, the torque adjustment commands received by each wheel constitute the superimposed coordinated control torque. These commands, in the form of positive values ​​(increasing driving force) or negative values ​​(increasing braking force), are superimposed on the driver's original driving or braking requests through the vehicle controller or electronic stability control system, achieving deep coordination with the front and rear wheel steering systems to jointly maintain the vehicle's driving posture and safety in complex road conditions.

[0237] This embodiment of the vehicle steering assist control method includes: acquiring the vehicle's driving data on the current road; determining the road surface adhesion coefficient based on the driving data; determining the front wheel superimposed torque and rear wheel steering angle based on the road surface adhesion coefficient and the driving data; determining the cooperative control torque based on the front wheel superimposed torque and rear wheel steering angle, and performing steering assist control on the vehicle. By calculating the front wheel superimposed torque and rear wheel steering angle adapted to different road conditions using the road surface adhesion coefficient, and performing cooperative control based on the front wheel superimposed torque and rear wheel steering angle, the overall handling stability and safety of the vehicle are ensured.

[0238] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of this application.

[0239] Reference Figure 2 This document illustrates a structural schematic diagram of a vehicle steering assist control system provided in an embodiment of this application, which may specifically include the following:

[0240] The data acquisition module 201 is used to acquire the vehicle's driving data on the current road;

[0241] The road surface adhesion coefficient determination module 202 is used to determine the road surface adhesion coefficient of the current road based on the driving data;

[0242] The first data processing module 203 is used to determine the superimposed torque of the front wheel and the rear wheel steering angle of the vehicle based on the road surface adhesion coefficient and the driving data. When the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, the rear wheel steering angle is calculated based on the yaw rate tracking term, the center of gravity sideslip angle stability term and the compensation angle. The compensation angle is used to offset the yaw torque caused by the difference in adhesion on both sides of the current road.

[0243] The second data processing module 204 is used to determine the cooperative control torque based on the superimposed torque of the front wheel and the steering angle of the rear wheel;

[0244] The control module 205 is used to perform steering assist control on the vehicle based on the rear wheel angle and the cooperative control torque.

[0245] In one embodiment of this application, the first data processing module 203 includes:

[0246] The strategy matching submodule is used to determine the corresponding steering assist control strategy based on the road surface adhesion coefficient.

[0247] The calculation submodule is used to determine the superimposed torque of the front wheels and the steering angle of the vehicle based on the steering assist control strategy and the driving data.

[0248] In one embodiment of this application, the steering assist control strategy includes: a high-adhesion conventional mode control strategy, a low-adhesion stable mode control strategy, and a split-road mode control strategy; the strategy matching submodule includes:

[0249] The first strategy matching unit is used to match a high-adhesion conventional mode control strategy when the road surface adhesion coefficient is greater than the first adhesion coefficient threshold. The high-adhesion conventional mode takes vehicle stability as the control target and sets a first feedforward gain function, a first angular velocity weight and a first centroid weight, wherein the first angular velocity weight is greater than the first centroid weight.

[0250] The second strategy matching unit is used to match a low-adhesion stability mode control strategy when the road surface adhesion coefficient is less than or equal to the first adhesion coefficient threshold. The low-adhesion stability mode control strategy takes vehicle agility as the control target and sets a second feedforward gain function, a second angular velocity weight and a second centroid weight, wherein the second angular velocity weight is less than the second centroid weight.

[0251] The third strategy matching unit is used to match a split-road mode control strategy when the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold. The split-road mode control strategy takes maintaining straight-line driving stability as the control objective, sets a third feedforward gain function, a third angular velocity weight and a third centroid weight, and determines a compensation angle based on the road surface adhesion coefficient. The compensation angle is used to offset the yaw moment caused by the different adhesion forces on both sides of the road.

[0252] In one embodiment of this application, the computing submodule includes:

[0253] The first calculation unit is used to determine the vehicle's feedback torque and risk level based on the driving data;

[0254] The second calculation unit is used to calculate the feedforward torque and the rear wheel angle under the steering assist control strategy based on the feedforward gain function and weight contained in the steering assist control strategy;

[0255] The third calculation unit is used to determine the corrective torque of the vehicle based on the risk level;

[0256] The fourth calculation unit is used to determine the front wheel superimposed torque based on the feedback torque, the feedforward torque, and the correction torque.

[0257] In one embodiment of this application, the second computing unit includes:

[0258] The high-adhesion calculation subunit is used to, under the high-adhesion conventional mode control strategy, match the first feedforward gain function, the first correction threshold, the first angular velocity weight, and the first center of gravity weight; calculate the feedforward torque based on the first feedforward gain function; and calculate the rear wheel steering angle based on the driving data, the first angular velocity weight, and the first center of gravity weight.

[0259] The low-adhesion calculation subunit is used to match the second feedforward gain function, the second correction threshold, the second angular velocity weight, and the second center of gravity weight under the low-adhesion stable mode control strategy; calculate the feedforward torque according to the second feedforward gain function; and calculate the rear wheel steering angle according to the driving data, the second angular velocity weight, and the second center of gravity weight.

[0260] The split-road surface calculation subunit is used to match the third feedforward gain function, the third correction threshold, the third angular velocity weight, and the third centroid weight under the split-road surface mode control strategy, and determine the compensation angle and compensation torque according to the road surface adhesion coefficient; calculate the feedforward torque according to the third feedforward gain function and the compensation torque; and calculate the rear wheel steering angle according to the driving data, the third angular velocity weight, the third centroid weight, and the compensation angle.

[0261] In one embodiment of this application, the second data processing module 204 includes:

[0262] An additional yaw moment calculation submodule is used to predict the additional yaw moment required to maintain vehicle stability based on the driving data and the road surface adhesion coefficient.

[0263] The collaborative control torque calculation submodule is used to determine the collaborative control torque required for each wheel of the vehicle based on the additional yaw moment, the superimposed torque of the front wheels, and the steering angle of the rear wheels.

[0264] In one embodiment of this application, the cooperative control torque calculation submodule includes:

[0265] A yaw moment contribution calculation unit is used to determine the yaw moment contribution value based on the superimposed torque of the front wheel and the steering angle of the rear wheel.

[0266] The yaw moment compensation calculation unit is used to determine the yaw moment compensation based on the difference between the additional yaw moment and the yaw moment contribution value.

[0267] The collaborative control torque calculation unit is used to match the collaborative control torque required for each wheel according to the compensated yaw moment and the preset distribution strategy.

[0268] As the system implementation is basically similar to the method implementation, it is described in a relatively simple way. For relevant details, please refer to the description of the system implementation.

[0269] like Figure 3As shown, in another embodiment provided in this application, an electronic device 300 is also provided, including a memory 310 and a processor 320. The memory 310 and the processor 320 are connected via a bus for communication. The memory 310 stores a computer program, which can run on the processor 320 to implement the above steps.

[0270] like Figure 4 As shown, in another embodiment provided in this application, a computer-readable storage medium 401 is also provided, which stores a computer program that implements the methods described in the above embodiments when executed by a processor.

[0271] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0272] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended content is intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0273] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0274] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0275] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0276] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0277] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended content is intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of this application.

[0278] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0279] The present invention provides a detailed description of a vehicle steering assistance control method. Specific examples have been used to illustrate the principle and implementation of the invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the invention. Therefore, the content of this specification should not be construed as a limitation of the invention.

Claims

1. A vehicle steering assist control method characterized by, The method includes: Obtain vehicle driving data on the current road; The road surface adhesion coefficient of the current road is determined based on the driving data; The front wheel superimposed torque and rear wheel steering angle of the vehicle are determined based on the road surface adhesion coefficient and the driving data, including: determining a corresponding steering assist control strategy based on the road surface adhesion coefficient; determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the steering assist control strategy and the driving data; when the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than a second adhesion coefficient threshold, the rear wheel steering angle is calculated based on the yaw rate tracking term, the center of gravity sideslip angle stability term, and the compensation angle. The compensation angle is calculated based on the difference between the longitudinal force on the left side and the longitudinal force on the right side, and is used to counteract the yaw moment caused by the difference in adhesion on both sides of the current road. The coordinated control torque is determined based on the superimposed torque of the front wheels and the steering angle of the rear wheels; The vehicle is subjected to steering assist control based on the rear wheel angle and the coordinated control torque.

2. The method of claim 1, wherein, The steering assist control strategy includes: a high-adhesion conventional mode control strategy, a low-adhesion stable mode control strategy, and a split-road mode control strategy. The step of determining the corresponding steering assist control strategy based on the road surface adhesion coefficient includes: When the road surface adhesion coefficient is greater than the first adhesion coefficient threshold, a high adhesion conventional mode control strategy is obtained; the high adhesion conventional mode takes vehicle stability as the control objective and sets a first feedforward gain function, a first angular velocity weight and a first centroid weight, wherein the first angular velocity weight is greater than the first centroid weight. When the road surface adhesion coefficient is less than or equal to the first adhesion coefficient threshold, a low adhesion stability mode control strategy is obtained; the low adhesion stability mode control strategy takes vehicle agility as the control target, and sets a second feedforward gain function, a second angular velocity weight and a second centroid weight, wherein the second angular velocity weight is less than the second centroid weight. When the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than the second adhesion coefficient threshold, a split road surface mode control strategy is obtained. The split road surface mode control strategy takes maintaining straight-line driving stability as the control objective, sets a third feedforward gain function, a third angular velocity weight and a third centroid weight, and determines the compensation turning angle based on the road surface adhesion coefficient.

3. The method of claim 2, wherein, Determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the steering assist control strategy and the driving data includes: The vehicle's feedback torque and risk level are determined based on the driving data. The feedforward torque and the rear wheel angle under the steering assist control strategy are calculated based on the feedforward gain function and weights included in the steering assist control strategy. The corrective torque of the vehicle is determined based on the risk level. The front wheel superimposed torque is determined based on the feedback torque, the feedforward torque, and the correction torque.

4. The method of claim 3, wherein, The step of calculating the feedforward torque and the rear wheel angle under the steering assist control strategy based on the feedforward gain function and weights included in the steering assist control strategy includes: Under the high-adhesion conventional mode control strategy, the first feedforward gain function, the first angular velocity weight, and the first center of mass weight are matched; the feedforward torque is calculated based on the first feedforward gain function; and the rear wheel steering angle is calculated based on the driving data, the first angular velocity weight, and the first center of mass weight. Under the low-adhesion stability mode control strategy, the second feedforward gain function, the second angular velocity weight, and the second center of gravity weight are matched and obtained; the feedforward torque is calculated based on the second feedforward gain function; and the rear wheel steering angle is calculated based on the driving data, the second angular velocity weight, and the second center of gravity weight. Under the aforementioned split-road mode control strategy, the third feedforward gain function, the third angular velocity weight, and the third centroid weight are matched and obtained, and the compensation angle and compensation torque are determined based on the road adhesion coefficient; the feedforward torque is calculated based on the third feedforward gain function and the compensation torque; and the rear wheel steering angle is calculated based on the driving data, the third angular velocity weight, the third centroid weight, and the compensation angle.

5. The method of claim 1, wherein, The step of determining the coordinated control torque based on the superimposed torque of the front wheels and the steering angle of the rear wheels includes: Predict the additional yaw moment required to maintain vehicle stability based on the driving data and the road surface adhesion coefficient. The required coordinated control torque for each wheel of the vehicle is determined based on the additional yaw moment, the superimposed torque of the front wheels, and the steering angle of the rear wheels.

6. The method of claim 5, wherein, The determination of the required coordinated control torque for each wheel of the vehicle based on the additional yaw moment, the front wheel superimposed torque, and the rear wheel steering angle includes: The yaw moment contribution value is determined based on the superimposed torque of the front wheels and the steering angle of the rear wheels; The compensation yaw moment is determined based on the difference between the additional yaw moment and the contribution value of the yaw moment; The required coordinated control torque for each wheel is matched according to the compensated yaw moment and the preset distribution strategy.

7. A vehicle steering assist control system characterized by comprising: The system includes: The data acquisition module is used to acquire vehicle driving data on the current road. The road surface adhesion coefficient determination module is used to determine the road surface adhesion coefficient of the current road based on the driving data; The first data processing module is used to determine the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the road surface adhesion coefficient and the driving data, including: determining a corresponding steering assist control strategy based on the road surface adhesion coefficient; determining the front wheel superimposed torque and rear wheel steering angle of the vehicle based on the steering assist control strategy and the driving data; when the difference between the road surface adhesion coefficient on the left side of the current road and the road surface adhesion coefficient on the right side of the current road is greater than a second adhesion coefficient threshold, the rear wheel steering angle is calculated based on the yaw rate tracking term, the center of gravity sideslip angle stability term, and the compensation angle, and the compensation angle is calculated based on the difference between the longitudinal force on the left side and the longitudinal force on the right side, and is used to counteract the yaw moment caused by the different adhesion forces on both sides of the current road; The second data processing module is used to determine the coordinated control torque based on the superimposed torque of the front wheels and the steering angle of the rear wheels; A control module is used to perform steering assist control on the vehicle based on the rear wheel angle and the cooperative control torque.

8. An electronic device, comprising: include: A memory, a processor, and a computer program stored on the memory, wherein the processor executes the computer program to implement the method of any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, which, when executed by a processor, implements the method as described in any one of claims 1-6.

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