Steering control method, vehicle and storage medium

Abstract

The invention provides a steering control method, a vehicle and a storage medium, the method is applied to the technical field of steering systems, and the method comprises the steps that dynamic characteristic parameters related to vehicle steering are obtained; obtaining a target proportionality coefficient between a rear wheel steering angle and a front wheel steering angle of the vehicle based on the dynamic characteristic parameters and a first relational expression; determining a first correction coefficient based on the target proportionality coefficient and a second relational expression; obtaining a target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle; and controlling the vehicle to perform four-wheel steering based on the target front-wheel steering angle. According to the method, the side slip angle can be zero by accurately matching the steering proportion of the front and rear wheels, the driving stability of the vehicle during steering is improved, and the yaw velocity gain of the vehicle during four-wheel steering is optimized.

Description

Technical Field

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

[0002] As the automotive industry continues to demand higher levels of stability, handling agility, and high-speed safety, four-wheel steering technology has gradually become one of the core solutions for improving vehicle dynamics. Existing four-wheel steering technologies are mostly based on traditional mechanical steering systems, achieving coordinated steering between the front and rear wheels by adding a rear-wheel steering mechanism. One of its core design goals is to reduce the sideslip angle of the vehicle's center of gravity during driving, thereby improving steering response accuracy and driving stability.

[0003] However, due to the limitations of traditional mechanical steering structures, the front wheel transmission ratio is fixed and cannot be dynamically adjusted according to operating conditions, which limits the adjustment range of the rear wheel steering angle (when the front wheel transmission ratio is fixed, an excessively large rear wheel steering angle will significantly change the yaw rate gain of the whole vehicle, thereby affecting driving safety, so the rear wheel steering angle needs to be limited). Because the adjustment range of the rear wheel steering angle is limited, the requirement for lateral force balance between the front and rear wheels cannot be met during driving, and thus the center of gravity sideslip angle cannot be effectively reduced during vehicle driving. Summary of the Invention

[0004] This application provides a steering control method, a vehicle, and a storage medium. The method can achieve a zero sideslip angle at the center of gravity by precisely matching the steering ratio of the front and rear wheels, thereby improving the driving stability of the vehicle during steering and optimizing the yaw rate gain of the vehicle during four-wheel steering.

[0005] In a first aspect, a steering control method is provided, comprising: acquiring dynamic characteristic parameters related to vehicle steering; obtaining a target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on the dynamic characteristic parameters and a first relation; wherein the first relation is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero; determining a first correction coefficient based on the target proportionality coefficient and a second relation; wherein the second relation is used to characterize the degree of difference between the yaw rate gains when the vehicle is steering in different steering modes; obtaining a target front wheel steering angle based on the first correction coefficient and the vehicle's initial front wheel steering angle; and controlling the vehicle to perform four-wheel steering based on the target front wheel steering angle.

[0006] The above technical solution acquires dynamic characteristic parameters related to vehicle steering, and based on these dynamic characteristic parameters and a first relationship, determines a target proportional coefficient. Since this first relationship is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero, the front and rear wheel steering ratios that achieve a zero center of gravity sideslip angle can be calculated based on the dynamic characteristic parameters and this first relationship. This allows for precise matching of the front and rear wheel steering ratios to achieve a zero center of gravity sideslip angle, thereby improving vehicle stability during steering. Furthermore, a first correction coefficient can be determined based on the target proportional coefficient and a second relationship. Since the second relationship characterizes the difference in yaw rate gain when the vehicle steering in different steering methods, based on the target proportional coefficient... The coefficient and the second relationship can calculate a specific value that reflects the difference in yaw rate gain when the vehicle is turned in different steering methods. Based on this value, the initial front wheel steering angle is corrected for four-wheel steering to obtain the target front wheel steering angle. The vehicle is then controlled to perform four-wheel steering based on the target front wheel steering angle. This ensures that the yaw rate gain when the vehicle is turned in four-wheel steering is consistent with the yaw rate gain when the vehicle is turned in other steering methods. This optimizes the yaw rate gain when the vehicle is turned in four-wheel steering, ensuring the consistency and safety of vehicle driving control. At the same time, it maximizes the advantages of four-wheel steering, avoids driver confusion caused by sudden changes in steering response, and effectively balances steering stability and handling comfort, thus effectively optimizing the vehicle's steering performance.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, before obtaining the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle, the method further includes: obtaining a second correction coefficient corresponding to the current vehicle speed; obtaining the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle includes: correcting the initial front wheel steering angle of the vehicle based on the first correction coefficient and the second correction coefficient to obtain the target front wheel steering angle.

[0008] The above technical solution obtains a second correction coefficient corresponding to the current vehicle speed, which can accurately adapt to the dynamic impact of vehicle speed changes on the yaw rate gain. This avoids the limitation that a single first correction coefficient can only achieve consistent yaw rate gains for four-wheel steering and front-wheel steering at a fixed vehicle speed, ensuring a stable gain matching basis can be established in different speed ranges. Based on the first and second correction coefficients, the initial front-wheel steering angle is corrected. This can both offset the gain difference between four-wheel steering and front-wheel steering through the first correction coefficient, ensuring the uniformity of steering response logic, and compensate for the gain difference caused by vehicle speed through the second correction coefficient. This can take into account both the handling flexibility and driving stability of the vehicle when performing four-wheel steering at different vehicle speeds.

[0009] Combining the first aspect and the above-mentioned implementation methods, in some implementation methods of the first aspect, based on dynamic characteristic parameters and the first relational formula, the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle is obtained, including: obtaining the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase; calculating the vehicle's front wheel steering angle based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, and the vehicle's wheelbase; calculating the vehicle's rear wheel steering angle based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase; and determining the ratio between the rear wheel steering angle and the front wheel steering angle as the target proportional coefficient.

[0010] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the second relation is expressed as the difference between the preset value and the first relation, and the first correction coefficient is determined based on the difference between the preset value and the target proportional coefficient.

[0011] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the second relation is generated in the following way: obtaining the first yaw rate gain when the vehicle performs front wheel steering, the second yaw rate gain when the vehicle performs four-wheel steering, and the first relation; and obtaining the second relation based on the first yaw rate gain, the second yaw rate gain, and the first relation.

[0012] Combining the first aspect and the above implementation methods, in some implementation methods of the first aspect, the first relation is generated in the following way: obtaining a two-degree-of-freedom vehicle dynamics model; replacing the front tire lateral force in the two-degree-of-freedom vehicle dynamics model with the product of the front axle side slip stiffness and the front wheel side slip angle, and replacing the rear tire lateral force in the two-degree-of-freedom vehicle dynamics model with the product of the rear axle side slip stiffness and the rear wheel side slip angle, to obtain a third relation after rewriting the two-degree-of-freedom vehicle dynamics model; replacing the front wheel side slip angle in the third relation with an expression related to the front wheel steering angle, and replacing the rear wheel side slip angle in the third relation with an expression related to the rear wheel steering angle, to obtain a fourth relation after rewriting the third relation; based on the fourth relation and preset constraints, obtaining the first relation; wherein, the preset constraint is that the vehicle's center of gravity side slip angle is equal to zero.

[0013] In combination with the first aspect and the above-mentioned implementation methods, in some implementation methods of the first aspect, the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle is obtained based on the dynamic characteristic parameters and the first relational formula, including: calculating the initial proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on the dynamic characteristic parameters and the first relational formula; determining the third correction coefficient corresponding to the current vehicle speed; and correcting the initial proportional coefficient based on the third correction coefficient to obtain the target proportional coefficient.

[0014] The above technical solution, based on vehicle dynamics characteristic parameters and the first relational formula, calculates the initial proportional coefficient. It can establish a basic matching logic for the steering angles of the rear and front wheels based on the vehicle's own dynamic characteristics. By accurately matching the steering ratios of the front and rear wheels, it achieves a zero sideslip angle, thereby improving the vehicle's driving stability during steering. It determines a third correction coefficient corresponding to the current vehicle speed, which can accurately adapt to the dynamic impact of vehicle speed changes on the vehicle's steering dynamics. This avoids the initial proportional coefficient from becoming unbalanced due to speed fluctuations, ensuring the adaptability of steering coordination at different vehicle speeds. By correcting the initial proportional coefficient with the third correction coefficient related to vehicle speed, it can effectively compensate for steering coordination deviations caused by vehicle speed. Ultimately, it ensures that the ratio of the steering angles of the rear and front wheels always adapts to the current vehicle speed and vehicle dynamics, achieving coordination, stability, and flexibility in steering response across the entire speed range, and improving the driving experience and driving safety in different driving scenarios.

[0015] In combination with the first aspect and the above implementation methods, in some implementation methods of the first aspect, obtaining the second correction coefficient corresponding to the current vehicle speed includes: obtaining the current vehicle speed; determining the second correction coefficient to be a value greater than 1 when the current vehicle speed is less than or equal to a preset vehicle speed; and determining the second correction coefficient to be a value less than 1 when the current vehicle speed is greater than the preset vehicle speed.

[0016] The above technical solution uses the vehicle's current speed as input for the precise matching of the second correction coefficient. When the current speed is less than or equal to the preset speed, the second correction coefficient is set to a value greater than 1. This amplifies the correction range of the initial front wheel steering angle, offsetting the difference in yaw rate gain between four-wheel steering and front wheel steering at low speeds, while maintaining the stability and controllability of low-speed steering without sacrificing the agility of small turning radii. When the current speed is greater than the preset speed, the second correction coefficient is set to a value less than 1. This reduces the correction range of the initial front wheel steering angle, adapting to changes in the gain ratio at high speeds, preventing overcorrection that could lead to an aggressive steering response, and enhancing stability at high speeds. Ultimately, this achieves precise matching between the correction coefficient and steering requirements across different speed ranges, ensuring consistent yaw rate gain between four-wheel steering and front wheel steering at all speeds, thus balancing handling experience and driving safety at both high and low speeds.

[0017] In a second aspect, a steering control device is provided, comprising: an acquisition module for acquiring dynamic characteristic parameters related to vehicle steering; a first generation module for obtaining a target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on the dynamic characteristic parameters and a first relational expression; wherein the first relational expression is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero; a determination module for determining a first correction coefficient based on the target proportionality coefficient and a second relational expression; wherein the second relational expression is used to characterize the degree of difference between the yaw rate gains when the vehicle is steering in different steering modes; a second generation module for obtaining a target front wheel steering angle based on the first correction coefficient and the vehicle's initial front wheel steering angle; and a control module for controlling the vehicle to perform four-wheel steering based on the target front wheel steering angle.

[0018] Thirdly, a vehicle is provided, including a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, causing the vehicle to perform the steering control method described in the first aspect and any possible implementation thereof.

[0019] Fourthly, a computer program product is provided, comprising: computer program code, which, when run on a computer, causes the computer to execute the steering control method in the first aspect and any possible implementation thereof.

[0020] Fifthly, a computer-readable storage medium is provided that stores computer program code, which, when executed on a computer, causes the computer to perform the steering control method described in the first aspect and any possible implementation thereof. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of a steering control method provided in an embodiment of this application; Figure 2 This is a schematic diagram illustrating the change of the target scaling factor with vehicle speed when the center of gravity sideslip angle is zero, provided in an embodiment of this application. Figure 3 This is a schematic diagram of the structure of a steering control device provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0022] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0023] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0024] As the automotive industry continues to demand higher levels of stability, handling agility, and high-speed safety, four-wheel steering technology has gradually become one of the core solutions for improving vehicle dynamics. Existing four-wheel steering technologies are mostly based on traditional mechanical steering systems, achieving coordinated steering between the front and rear wheels by adding a rear-wheel steering mechanism. One of its core design goals is to reduce the sideslip angle of the vehicle's center of gravity during driving, thereby improving steering response accuracy and driving stability.

[0025] However, due to the limitations of traditional mechanical steering structures, the front wheel transmission ratio is fixed and cannot be dynamically adjusted according to operating conditions, which limits the adjustment range of the rear wheel steering angle (when the front wheel transmission ratio is fixed, an excessively large rear wheel steering angle will significantly change the yaw rate gain of the whole vehicle, thereby affecting driving safety, so the rear wheel steering angle needs to be limited). Because the adjustment range of the rear wheel steering angle is limited, the requirement for lateral force balance between the front and rear wheels cannot be met during driving, and thus the center of gravity sideslip angle cannot be effectively reduced during vehicle driving.

[0026] To address the aforementioned technical problems, this application provides a steering control method. The method is executed by a vehicle equipped with a steer-by-wire system, specifically a controller within that system. This application replaces the traditional mechanical steering structure with a steer-by-wire structure, changing the front-wheel drive ratio from a fixed form to one that can be dynamically adjusted according to operating conditions. This increases the adjustability of the vehicle's yaw rate. Thus, even when the rear wheel steering angle is adjusted to achieve the ideal match of zero sideslip angle, the impact of rear wheel steering on the vehicle's yaw rate gain can be offset by dynamically correcting the front wheel steering angle. This ensures driving safety while achieving precise control of the sideslip angle, thereby improving the vehicle's steering stability and handling performance.

[0027] Among them, the steer-by-wire system is an independent system. Unlike the traditional mechanical steering system, the steer-by-wire system eliminates the direct physical connection between the steering wheel and the steering gear. It uses electronic signals to transmit the driver's steering intention to the vehicle's steering actuators to control the vehicle's steering. In other words, vehicles equipped with a steer-by-wire system do not have mechanical linkages (such as steering column, rack, etc.) between the steering wheel and the wheels; steering control is achieved entirely through "steer-by-wire" (i.e., electronic signals).

[0028] Figure 1 This is a schematic flowchart of a steering control method provided in an embodiment of this application.

[0029] For example, such as Figure 1 As shown, this method is applied to a vehicle equipped with a steer-by-wire system, and the method 100 includes: Step 101: Obtain the dynamic characteristic parameters related to vehicle steering.

[0030] Step 102: Based on the dynamic characteristic parameters and the first relational formula, obtain the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle.

[0031] The first relationship is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero.

[0032] Step 103: Determine the first correction coefficient based on the target proportional coefficient and the second relationship.

[0033] The second relationship is used to characterize the degree of difference between the yaw rate gains when the vehicle is steering in different steering methods.

[0034] Step 104: Based on the first correction coefficient and the initial front wheel steering angle of the vehicle, obtain the target front wheel steering angle.

[0035] Step 105: Control the vehicle to perform four-wheel steering based on the target front wheel steering angle.

[0036] In this embodiment, dynamic characteristic parameters related to vehicle steering are obtained. Based on these dynamic characteristic parameters and a first relationship, a target proportional coefficient can be determined. Since the first relationship is the ratio between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero, the front and rear wheel steering ratios that achieve a zero center of gravity sideslip angle can be calculated based on the dynamic characteristic parameters and the first relationship. This allows for precise matching of the front and rear wheel steering ratios to achieve a zero center of gravity sideslip angle, thereby improving vehicle stability during steering. Furthermore, a first correction coefficient can be determined based on the target proportional coefficient and a second relationship. Since the second relationship characterizes the difference in yaw rate gain when the vehicle steering in different steering methods, a correction coefficient can be determined based on the target proportional coefficient. The example coefficient and the second relationship can calculate a specific value that reflects the degree of difference in yaw rate gain when the vehicle is turned in different steering methods. Based on this value, the initial front wheel steering angle during four-wheel steering is corrected to obtain the target front wheel steering angle. The vehicle is then controlled to perform four-wheel steering based on the target front wheel steering angle. This ensures that the yaw rate gain during four-wheel steering is consistent with the yaw rate gain when the vehicle is turned in other steering methods, thereby optimizing the yaw rate gain during four-wheel steering. This ensures the consistency and safety of vehicle driving control, maximizes the advantages of four-wheel steering, avoids driver confusion caused by sudden changes in steering response, effectively balances steering stability and handling comfort, and effectively optimizes the vehicle's steering performance.

[0037] The following is about Figure 1 The specific implementation methods of each step in the illustrated embodiment are explained below: In step 101, the aforementioned vehicle specifically refers to a vehicle equipped with a steer-by-wire system. As mentioned earlier, vehicles equipped with a steer-by-wire system do not have mechanical linkages (such as steering column, rack, etc.) between the steering wheel and the front wheels; steering control is achieved entirely through "steer-by-wire" (i.e., electronic signals), meaning that the transmission ratio of the front wheels in a vehicle equipped with a steer-by-wire system is variable.

[0038] The aforementioned dynamic characteristic parameters related to vehicle steering specifically refer to the set of parameters that determine the vehicle's steering dynamics (such as yaw rate and sideslip angle) when the vehicle is steering.

[0039] For example, the aforementioned dynamic characteristic parameters may include, but are not limited to: vehicle mass, center of gravity position parameters (including the distance from the center of gravity to the front axle and the distance from the center of gravity to the rear axle), current vehicle speed, front axle lateral stiffness, rear axle lateral stiffness, steering wheel angle, front wheel steering angle, and rear wheel steering angle.

[0040] The aforementioned vehicle mass refers to the total mass of the vehicle, which can be the vehicle's unloaded mass or the actual mass estimated by the vehicle's controller, expressed in kilograms (kg). The vehicle's unloaded mass is an inherent parameter of the vehicle, which can usually be directly measured using a vehicle weighing platform before the vehicle leaves the factory and stored directly in the vehicle's storage module. The controller can directly read this unloaded mass from the vehicle's storage module. Alternatively, the vehicle's controller can estimate the actual mass of the vehicle in real time using a longitudinal dynamics model, combined with parameters such as the vehicle's driving force, braking force, acceleration, and the current road slope.

[0041] The aforementioned center of gravity position parameters refer to the distances from the vehicle's center of gravity to the front axle and the distances from the vehicle's center of gravity to the rear axle. Based on these parameters, the vehicle's wheelbase can also be calculated (wheelbase = distance from center of gravity to front axle + distance from center of gravity to rear axle). These center of gravity position parameters are typically inherent to the vehicle and can usually be measured using a center of gravity position test bench before the vehicle leaves the factory. They are then directly stored in the vehicle's storage module, and the controller can directly read these parameters from the vehicle's storage module.

[0042] The aforementioned current vehicle speed typically refers to the vehicle's longitudinal speed (speed along the x-axis of the vehicle body), measured in kilometers per hour (km / h). Wheel speeds are usually detected by wheel speed sensors, and the vehicle's controller determines the current vehicle speed based on the measured wheel speeds.

[0043] The aforementioned front axle lateral stiffness and rear axle lateral stiffness represent the lateral forces generated by the front and rear wheels of the vehicle under a unit slip angle, respectively, expressed in Newton-radians (N / rad). The front and rear axle lateral stiffness are typically inherent parameters of the vehicle. They are usually calculated by testing the lateral stiffness of individual tires on a tire test bench before the vehicle leaves the factory, combined with the front and rear axle loads, and directly stored in the vehicle's storage module. The controller can directly read the front and rear axle lateral stiffness from the vehicle's storage module.

[0044] The steering wheel angle mentioned above usually refers to the angle at which the driver turns the steering wheel, measured in degrees (°) or radians (rad). It can typically be measured using a steering wheel angle sensor located on the vehicle's steering column.

[0045] The aforementioned front wheel steering angle typically refers to the deflection angle of the vehicle's front wheels relative to the vehicle's longitudinal axis, measured in degrees (°) or radians (rad). For vehicles equipped with a steer-by-wire system, the vehicle's controller can directly read the signal values ​​used to control the front wheels, or it can be measured by angle sensors in the front wheel steering actuators.

[0046] The aforementioned rear wheel steering angle typically refers to the deflection angle of the vehicle's rear wheels relative to the vehicle's longitudinal axis, measured in degrees (°) or radians (rad). It can usually be measured by an angle sensor in the rear wheel steering actuator.

[0047] Understandably, by acquiring the dynamic characteristic parameters related to vehicle steering, we can provide accurate data support for the calculation of subsequent parameters such as the target proportional coefficient and the first correction coefficient, ensuring that the calculation results of each parameter are highly consistent with the actual driving state and inherent dynamic characteristics of the vehicle, thereby providing a solid data foundation for the precise control of the vehicle steering angle and the optimization of steering performance.

[0048] In step 102, the target ratio coefficient between the rear wheel steering angle and the front wheel steering angle is the ratio between the rear wheel steering angle and the front wheel steering angle. By calculating the target ratio coefficient, the specific ratio between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero can be accurately determined. Based on the target ratio coefficient, the rear wheel steering angle and the front wheel steering angle of the vehicle are controlled to ensure that the vehicle's center of gravity sideslip angle approaches zero, thereby improving the vehicle's steering stability from the root.

[0049] The aforementioned sideslip angle refers to the angle between the actual velocity direction at the vehicle's center of gravity and the vehicle's longitudinal axis (i.e., the direction of vehicle movement), measured in degrees (°) or radians (rad). This sideslip angle can be approximated as the ratio of the vehicle's lateral velocity to its longitudinal velocity.

[0050] Understandably, the aforementioned sideslip angle is one of the core indicators for measuring vehicle steering stability. Under normal driving and steering conditions, the smaller the sideslip angle, the less the vehicle deflects laterally during cornering, the more stable the driving posture, and the higher the steering stability. Therefore, reducing the sideslip angle (i.e., controlling the sideslip angle to zero) can effectively reduce the discomfort experienced by the driver and passengers due to lateral tilting and deflection of the vehicle, significantly improving ride comfort and safety during cornering.

[0051] Furthermore, the first formula, which is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the center of gravity sideslip angle is zero, can be obtained. The above dynamic characteristic parameters are then substituted into the first formula to obtain the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle when the center of gravity sideslip angle of the vehicle is zero.

[0052] In some embodiments, the first relation can specifically refer to the following formula (1): Formula (1) In formula (1), P represents the ratio between the rear wheel steering angle and the front wheel steering angle of the vehicle. The front wheel steering angle of the vehicle. This refers to the rear wheel steering angle of the vehicle. This represents the vehicle's current speed. This is the distance from the vehicle's center of gravity to its front axle. Let m be the distance from the vehicle's center of mass to its rear axle, and m be the vehicle's mass. For the front axle lateral stiffness of the vehicle, L represents the rear axle lateral stiffness of the vehicle, and L represents the wheelbase of the vehicle.

[0053] It is understandable that the front wheel steering angle in the above formula (1) and rear wheel steering angle These are variables that will be dynamically adjusted based on the target proportional coefficient later, and do not need to be obtained when calculating the target proportional coefficient. The parameters in formula (1) above, except for the front wheel steering angle and the rear wheel steering angle, are the actual parameters currently obtained by the vehicle's controller and are required to calculate the target proportional coefficient. The specific meanings and acquisition methods of each parameter in formula (1) above can be found in the preceding text and will not be repeated here.

[0054] In some embodiments, based on dynamic characteristic parameters and a first relational expression, the target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle is obtained, including: acquiring the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase; calculating the vehicle's front wheel steering angle based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, and the vehicle's wheelbase; calculating the vehicle's rear wheel steering angle based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase; and determining the ratio between the rear wheel steering angle and the front wheel steering angle as the target proportionality coefficient.

[0055] It is understood that the specific meanings and acquisition methods of the above parameters can be referred to the above text, and will not be repeated here.

[0056] For example, assuming the vehicle's mass is 1500 kg, the distance from the vehicle's center of gravity to the front axle is 1.2 m, the distance from the vehicle's center of gravity to the rear axle is 1.5 m, the front axle lateral stiffness is -52000 N / rad, the rear axle lateral stiffness is -58000 N / rad, the wheelbase is 2.7 m, and the current vehicle speed is 50 km / h ≈ 13.9 m / s, substituting the above parameters into formula (1), the target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle when the center of gravity lateral angle is zero can be calculated as: P = [-1.5 + (1500 * 1.2 * 13.9] 2 / 2.7*-58000)] / [1.2+(1500*1.5*13.9 2 / 2.7*-58000)]=[-1.5+(347778 / -156600)] / [1.2+(434722.5 / -140400)]=-3.72 / -1.89=1.97.

[0057] Figure 2 This is a schematic diagram illustrating the change of the target proportional coefficient with vehicle speed when the center of gravity sideslip angle is zero, provided in an embodiment of this application.

[0058] For example, such as Figure 2 As shown, when the vehicle's current speed is low (e.g., Figure 2 When the speed is less than 75 km / h, the front and rear wheels usually turn in opposite directions, meaning the target proportion coefficient is usually negative.

[0059] It is understandable that when a vehicle is performing four-wheel steering at low speed, in order to reduce the turning radius and reduce the difficulty of steering, the front and rear wheels can be controlled to turn in opposite directions, such as the front wheels turning right and the rear wheels turning left.

[0060] like Figure 2 As shown, when the vehicle's current speed is high (e.g., Figure 2 When the speed is greater than 75 km / h, the front and rear wheels usually turn in the same direction, meaning the target proportioning coefficient is usually positive.

[0061] Understandably, when a vehicle is performing four-wheel steering at high speed, in order to avoid significant body deviation and maintain consistent steering response, the front and rear wheels can be controlled to steer in the same direction, such as the front wheels turning right and the rear wheels turning right.

[0062] The above Figure 2 The curve showing the target proportional coefficient changing with vehicle speed when the center of gravity sideslip angle is zero is only one example.

[0063] For example, the first relationship between the rear wheel steering angle and the front wheel steering angle when the center of gravity sideslip angle is zero can usually be derived based on a two-degree-of-freedom vehicle dynamics model.

[0064] In some embodiments, the first relation is generated by the following steps S31-S34: S31, Obtain the two-degree-of-freedom vehicle dynamics model.

[0065] Specifically, the above two-degree-of-freedom vehicle dynamics model can be referred to as the following formula (2): Formula (2) In the above formula (2), m is the mass of the vehicle. The rate of change of the vehicle's center of gravity sideslip angle. This represents the vehicle's current speed. Let yaw rate be the vehicle's angular velocity. This refers to the lateral force on the vehicle's front tires. This refers to the lateral force on the rear tires of the vehicle. Let be the moment of inertia of the vehicle along the z-axis. The rate of change of the vehicle's yaw rate. This is the distance from the vehicle's center of gravity to its front axle. This is the distance from the vehicle's center of gravity to its rear axle.

[0066] Among them, the aforementioned rate of change of centroid side deflection angle This refers to the rate of change of the angle between the velocity direction at the vehicle's center of gravity and the vehicle's longitudinal axis (center of gravity sideslip angle) over time, measured in rad / s. 2 This is used to reflect the dynamic response speed of the sideslip angle. Specifically, the aforementioned rate of change of the centroid sideslip angle can be obtained by performing time derivative calculations on the real-time measured value of the centroid sideslip angle.

[0067] The above yaw rate Yaw rate refers to the angular velocity of a vehicle's rotation around its vertical axis (z-axis), measured in rad / s. It directly reflects the "fishtailing" or "straightening" tendency of a vehicle when turning. The yaw rate mentioned above can usually be directly measured by the gyroscope in the vehicle's Inertial Measurement Unit (IMU).

[0068] The aforementioned lateral force of the front tire This refers to the force exerted by the front tires in contact with the ground, perpendicular to the direction of wheel rolling. It is measured in Newtons (N) and is the primary force source providing lateral acceleration when the vehicle is turning. The aforementioned lateral force on the front tires can typically be directly measured using wheel force sensors.

[0069] The aforementioned lateral force of the rear tire This refers to the lateral force exerted by the rear tires when they contact the ground, measured in Newtons (N), and affects the vehicle's steering stability (such as oversteer and understeer). The aforementioned lateral force on the rear tires can also be directly measured using wheel force sensors.

[0070] The moment of inertia of the above-mentioned vehicle along the z-axis This refers to the magnitude of a vehicle's inertia when it rotates about its vertical axis, and the unit is kg. m 2 Moment of inertia The larger the value, the slower the vehicle's yaw response and the greater the moment of inertia. These are inherent parameters of the vehicle. The moment of inertia of the vehicle along the z-axis is usually measured through a torsional pendulum test.

[0071] The aforementioned rate of change of yaw rate refers to the angular acceleration of the vehicle rotating about its own vertical axis (z-axis), and the unit is rad / s. 2 This is used to reflect how quickly a vehicle's yaw rate changes over time. The aforementioned rate of change of yaw rate is usually obtained by differentiating the measured yaw rate over time.

[0072] It is understandable that the above two-degree-of-freedom vehicle dynamics model can also be called the "lateral force balance and yaw moment balance equation". In order to simplify the above two-degree-of-freedom vehicle dynamics model and reduce the complexity of calculation, the above two-degree-of-freedom vehicle dynamics model can be rewritten.

[0073] S32, replace the lateral force of the front tire in the two-degree-of-freedom vehicle dynamics model with the product of the front axle lateral stiffness and the front wheel slip angle, and replace the lateral force of the rear tire in the two-degree-of-freedom vehicle dynamics model with the product of the rear axle lateral stiffness and the rear wheel slip angle, to obtain the third relation after rewriting the two-degree-of-freedom vehicle dynamics model.

[0074] Specifically, the aforementioned lateral force of the front tire can be expressed by the following formula (3): Formula (3) In formula (3), For the front axle lateral stiffness of the vehicle, This refers to the front wheel slip angle of the vehicle.

[0075] As mentioned earlier, the front axle lateral stiffness refers to the lateral force generated by the front wheel of a vehicle under a unit slip angle, measured in Newton-radians (N / rad). Front axle lateral stiffness is typically an inherent parameter of the vehicle. It can usually be calculated by testing the lateral stiffness of a single tire on a tire test bench before the vehicle leaves the factory, combined with the front axle load, and directly stored in the vehicle's storage module. The controller can directly read the front axle lateral stiffness from the vehicle's storage module.

[0076] The aforementioned front wheel slip angle refers to the angle between the actual direction of movement of the front wheel and the wheel's own rolling direction (the direction of the wheel hub plane normal), measured in radians (rad). This front wheel slip angle can typically be measured using an optical slip angle measuring instrument or a wheel six-component force sensor in the vehicle.

[0077] The lateral force of the rear tire mentioned above can be specifically expressed by the following formula (4): Formula (4) In formula (4), For the rear axle lateral stiffness of the vehicle, This refers to the rear wheel slip angle of the vehicle.

[0078] As mentioned earlier, the rear axle lateral stiffness refers to the lateral force generated by the rear wheel of a vehicle under a unit slip angle, measured in Newton-radians (N / rad). Rear axle lateral stiffness is typically an inherent parameter of the vehicle. It can usually be calculated by testing the lateral stiffness of a single tire on a tire test bench after the vehicle leaves the factory, combined with the rear axle load, and directly stored in the vehicle's storage module. The controller can directly read the rear axle lateral stiffness from the vehicle's storage module.

[0079] The rear wheel slip angle mentioned above refers to the angle between the actual direction of movement of the rear wheel and the direction of its own rolling (the direction of the wheel hub plane normal), and the unit is radians (rad). Similar to the front wheel slip angle, the rear wheel slip angle can usually be measured by an optical slip angle measuring instrument or a wheel six-component force sensor in the vehicle.

[0080] Furthermore, replace the above formula (2) with the above formulas (3) and (4). and We can obtain the following formula (5): Formula (5) It is understandable that the above formula (5) is the third relation after rewriting the two-degree-of-freedom vehicle dynamics model.

[0081] Furthermore, in order to transform the intermediate state parameters (i.e., front wheel slip angle and rear wheel slip angle) in the third relationship into measurable variables, the front wheel slip angle and rear wheel slip angle in the third relationship can be further replaced.

[0082] S33, replace the front wheel slip angle in the third relation with an expression related to the front wheel steering angle, and replace the rear wheel slip angle in the third relation with an expression related to the rear wheel steering angle, to obtain the fourth relation after rewriting the third relation.

[0083] Specifically, the aforementioned front wheel slip angle can be expressed by the following formula (6): Formula (6) In the above formula (6), The front wheel steering angle of the vehicle. The sideslip angle is the vehicle's center of gravity. This represents the vehicle's current speed. This is the distance from the vehicle's center of gravity to its front axle. Let be the yaw rate of the vehicle.

[0084] The aforementioned front wheel steering angle typically refers to the deflection angle of the vehicle's front wheels relative to the vehicle's longitudinal axis, measured in degrees (°) or radians (rad). For vehicles equipped with a steer-by-wire system, the vehicle's controller can directly read the signal values ​​used to control the front wheels, or it can be measured by angle sensors in the front wheel steering actuators.

[0085] The aforementioned sideslip angle refers to the angle between the actual velocity direction at the vehicle's center of gravity and the vehicle's longitudinal axis (the forward reference direction of the vehicle's design), expressed in radians (rad) or degrees (°). This sideslip angle can usually be estimated based on the vehicle's lateral and longitudinal velocities.

[0086] The aforementioned current vehicle speed typically refers to the vehicle's longitudinal speed (speed along the x-axis of the vehicle body), measured in kilometers per hour (km / h). Wheel speeds are usually detected by wheel speed sensors, and the vehicle's controller determines the current vehicle speed based on the measured wheel speeds.

[0087] The distance from the center of gravity to the front axle of the vehicle mentioned above refers to the horizontal distance from the vehicle's center of gravity (the center of mass of the entire vehicle) to the centerline of the front axle, and the unit is meters (m). This distance from the center of gravity to the front axle is usually an inherent parameter of the vehicle, which can usually be measured by a center of gravity position test bench before the vehicle leaves the factory and stored directly in the vehicle's storage module. The controller can directly read the distance from the center of gravity to the front axle of the vehicle from the vehicle's storage module.

[0088] The above yaw rate This refers to the angular velocity of the vehicle's rotation about its vertical axis (z-axis), measured in rad / s. The yaw rate described above can typically be measured directly by a gyroscope in the vehicle's IMU.

[0089] The aforementioned rear wheel slip angle can be specifically expressed by the following formula (7): Formula (7) In the above formula (7), This refers to the rear wheel steering angle of the vehicle. The sideslip angle is the vehicle's center of gravity. This represents the vehicle's current speed. This is the distance from the vehicle's center of gravity to its rear axle. Let be the yaw rate of the vehicle.

[0090] The aforementioned rear wheel steering angle typically refers to the deflection angle of the vehicle's rear wheels relative to the vehicle's longitudinal axis, measured in degrees (°) or radians (rad). It can usually be measured by an angle sensor in the rear wheel steering actuator.

[0091] The aforementioned sideslip angle refers to the angle between the actual velocity direction at the vehicle's center of gravity and the vehicle's longitudinal axis (the forward reference direction of the vehicle's design), expressed in radians (rad) or degrees (°). This sideslip angle can usually be estimated based on the vehicle's lateral and longitudinal velocities.

[0092] The aforementioned current vehicle speed typically refers to the vehicle's longitudinal speed (speed along the x-axis of the vehicle body), measured in kilometers per hour (km / h). Wheel speeds are usually detected by wheel speed sensors, and the vehicle's controller determines the current vehicle speed based on the measured wheel speeds.

[0093] The distance from the center of gravity to the rear axle of the vehicle mentioned above refers to the horizontal distance from the vehicle's center of gravity (center of mass) to the centerline of the rear axle, measured in meters (m). This distance is usually an inherent parameter of the vehicle and can typically be measured using a center of gravity position test bench before the vehicle leaves the factory. It is then stored directly in the vehicle's storage module, and the controller can directly read the distance from the center of gravity to the rear axle from the vehicle's storage module.

[0094] The above yaw rate This refers to the angular velocity of the vehicle's rotation about its vertical axis (z-axis), measured in rad / s. The yaw rate described above can typically be measured directly by a gyroscope in the vehicle's IMU.

[0095] Furthermore, replace the above formula (5) with the above formulas (6) and (7). and We can obtain the following formula (8): Formula (8) It is understandable that by transforming the third relation, the uncontrollable intermediate parameters (such as the side slip angle) in the third relation can be eliminated, and the parameters in the resulting fourth relation are unified into measurable input parameters and inherent parameters.

[0096] Furthermore, in order to derive the proportional relationship between the front wheel steering angle and the rear wheel steering angle of the vehicle when the center of gravity sideslip angle is zero, i.e., the first relationship, the center of gravity sideslip angle in the above formula (8) can be set to zero.

[0097] S34, based on the fourth relation and preset constraints, yields the first relation.

[0098] The aforementioned preset constraint condition is that the vehicle's center of gravity sideslip angle is equal to zero.

[0099] Specifically, we can set the centroid sideslip angle in the fourth relation to zero to obtain the first relation.

[0100] Specifically, by setting the centroid sideslip angle β in the above formula (8) to 0, we can obtain the following formula (9): Formula (9) Furthermore, based on the second formula in the above formula (9), we can obtain the following formula (10): Formula (10) Substitute the above formula (10) into the first formula in the above formula (9), and use We can obtain the following formula (11): Formula (11) Furthermore, by combining the wheelbase L=a+b, simplifying the above formula (11), we can obtain the following formula (12) (which is also the above formula (1)): Formula (12) It is understood that the above formula (12) is the proportional relationship between the rear wheel steering angle and the front wheel steering angle of the vehicle when the vehicle's center of gravity sideslip angle is zero, i.e., the above first relationship. After obtaining the above first relationship, the first relationship can be stored in the vehicle's storage module.

[0101] In step 103, the vehicle controller can substitute the currently measured dynamic characteristic parameters of the vehicle into formula (12) to obtain the target proportional coefficient.

[0102] The second relationship described above is used to characterize the degree of difference between the yaw rate gains when the vehicle turns in different steering modes.

[0103] For example, the aforementioned second relationship can specifically be a proportional relationship between the first yaw rate gain when the vehicle is performing four-wheel steering and the second yaw rate gain when the vehicle is performing front-wheel steering.

[0104] In some embodiments, the second relation is represented as the difference between a preset value and the first relation, and the first correction coefficient can be specifically determined based on the difference between the preset value and the target proportional coefficient.

[0105] The aforementioned preset difference is obtained based on the derivation result, and can specifically be 1.

[0106] For example, the second relation above can be specifically referred to as formula (13) below: Formula (13) In the above formula (13), The first yaw rate gain when the vehicle performs four-wheel steering. The second yaw rate gain when the vehicle is steering with the front wheels. The front wheel steering angle of the vehicle. Let be the rear wheel steering angle of the vehicle, and P be the ratio between the rear wheel steering angle and the front wheel steering angle.

[0107] It is understandable that the above formula (13) can also be stored in the vehicle's storage module. After the vehicle's controller calculates the target proportional coefficient based on the above formula (12), it can substitute the target proportional coefficient into the above formula (13) to obtain the first correction coefficient.

[0108] For example, assuming that the target proportional coefficient P = 0.5 is calculated based on the above formula (12), the first correction coefficient can be calculated as 2 based on the above formula (13).

[0109] For example, the above formula (13) can usually be derived based on the formula for calculating the yaw rate when the vehicle is turning with four wheels and the formula for calculating the yaw rate when the vehicle is turning with the front wheels.

[0110] In some embodiments, the above second relation, i.e., the above formula (13), can be derived by the following S41-S43: S41, acquire the first yaw rate gain when the vehicle is turning the front wheels and the second yaw rate gain when the vehicle is turning the four wheels.

[0111] Specifically, the first yaw rate of the vehicle when the front wheels turn can be obtained first, and it can be calculated using the following formula (14): Formula (14) In the above formula (14), The first yaw rate when the vehicle steers with its front wheels. This represents the vehicle's current speed. This refers to the vehicle's wheelbase. This is the understeer coefficient of the vehicle. This refers to the steering angle of the vehicle's front wheels.

[0112] The understeer coefficient mentioned above measures the degree of match between the vehicle's actual steering trajectory and the steering wheel input command during steering. A positive understeer coefficient indicates understeer, while a negative understeer coefficient indicates oversteer.

[0113] For example, the aforementioned understeering coefficient can typically be calculated using the following formula (15): Formula (15) In the above formula (15), This is the distance from the vehicle's center of gravity to its front axle. Let m be the distance from the vehicle's center of mass to its rear axle, and m be the vehicle's mass. For the front axle lateral stiffness of the vehicle, L represents the rear axle lateral stiffness of the vehicle, and L represents the wheelbase of the vehicle.

[0114] It is understandable that the methods for obtaining the parameters in the above formulas (14) and (15) can refer to the methods described above, and will not be repeated here.

[0115] Furthermore, the second yaw rate when the vehicle is performing four-wheel steering can also be obtained.

[0116] Specifically, the second yaw rate mentioned above can be calculated using the following formula (16): Formula (16) In the above formula (16), The second yaw rate, This represents the vehicle's current speed. This refers to the vehicle's wheelbase. This is the understeer coefficient of the vehicle. The front wheel steering angle of the vehicle. This is the rear wheel steering angle of the vehicle.

[0117] It is understandable that the methods for obtaining the parameters in the above formula (16) can refer to the methods described above, and will not be repeated here.

[0118] Furthermore, based on the above-mentioned calculation formula for the first yaw rate and the steering angle of the vehicle's steering wheel, the calculation formula for the first yaw rate gain can be derived.

[0119] Specifically, the formula for calculating the first yaw rate gain can be obtained by dividing the above formula (14) by the steering angle of the steering wheel.

[0120] For example, the formula for calculating the first yaw rate gain can be referred to the following formula (17): Formula (17) In the above formula (17), denoted as the first yaw rate gain, and s as the steering angle of the steering wheel.

[0121] The steering angle mentioned above usually refers to the angle at which the driver turns the steering wheel, measured in degrees (°) or radians (rad). It is typically measured using a steering wheel angle sensor located on the vehicle's steering column.

[0122] It is understandable that the methods for obtaining the parameters in the above formula (17) can refer to the methods described above, and will not be repeated here.

[0123] Furthermore, based on the calculation formula for the second yaw rate and the steering angle of the vehicle's steering wheel, the calculation formula for the second yaw rate gain can be derived.

[0124] Specifically, similar to the previous text, dividing the above formula (16) by the steering angle of the steering wheel will give the formula for calculating the second yaw rate gain.

[0125] For example, the formula for calculating the second yaw rate gain can be referred to the following formula (18): Formula (18) In the above formula (18), denoted as the second yaw rate gain, and s as the steering angle of the steering wheel.

[0126] It is understandable that the methods for obtaining the parameters in the above formula (18) can refer to the methods described above, and will not be repeated here.

[0127] S42, obtain the first relation.

[0128] It is understandable that the first relation above can specifically be the formula (1) mentioned above. Specifically, it can be expressed as: .

[0129] S43. Based on the first yaw rate gain, the second yaw rate gain, and the first relational expression, the second relational expression is obtained.

[0130] It is understandable that, based on the above formulas (17) and (18), the proportional relationship between the first yaw rate gain and the second yaw rate gain can be obtained, specifically as shown in the following formula (19): Formula (19) In the above formula (19), The first yaw rate gain when the vehicle performs four-wheel steering. The second yaw rate gain when the vehicle is steering with the front wheels. The front wheel steering angle of the vehicle. This is the rear wheel steering angle of the vehicle.

[0131] The rear wheel steering angle in the above formula (19) Replace with the one obtained from the first relation. Thus, we can obtain the following formula (20) (i.e., the above formula (13)): Formula (20) In the above formula (20), P is the target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle.

[0132] It is understood that the above formula (20) is the proportional relationship between the first yaw rate gain when the vehicle is performing four-wheel steering and the second yaw rate gain when the vehicle is performing front-wheel steering, i.e., the above second relationship. After obtaining the above second relationship, the second relationship can be stored in the vehicle's storage module.

[0133] Furthermore, after the vehicle controller calculates the target proportional coefficient P based on the above formula (12), it can substitute the target proportional coefficient P into the above formula (20) to obtain the first correction coefficient.

[0134] For example, assuming the target scaling factor P is calculated to be 0.6, substituting the target scaling factor into the above formula (20) yields a first correction factor of 2.5.

[0135] Furthermore, in order to optimize the steering characteristics of the vehicle under different operating conditions, the embodiments of this application can also optimize the target proportional coefficient calculated above to adapt the turning performance of the vehicle at different speeds.

[0136] In some embodiments, obtaining the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle of a vehicle based on dynamic characteristic parameters and a first relation includes: calculating the initial proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on dynamic characteristic parameters and the first relation; determining a third correction coefficient corresponding to the current vehicle speed; and correcting the initial proportional coefficient based on the third correction coefficient to obtain the target proportional coefficient.

[0137] It is understandable that after the vehicle controller obtains the dynamic characteristic parameters, it can substitute the dynamic characteristic parameters into the above formula (12) to calculate the initial proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle.

[0138] Because vehicle requirements differ at different speeds, for example, when a vehicle is traveling at low speed, it is usually necessary to ensure stability and controllability when turning. This can usually be achieved by controlling the rear wheels to turn slightly, and the initial proportional coefficient can be appropriately adjusted to a slightly smaller value. When a vehicle is traveling at high speed, it is usually necessary to ensure the response speed when turning. This can usually be achieved by correcting the zero center of gravity sideslip angle to coordinate the steering of the front and rear wheels, reduce the sideslip when turning, improve straight-line driving stability and cornering follow-through, and maintain the current initial proportional coefficient.

[0139] For example, a first mapping relationship between each vehicle speed and the third correction coefficient (denoted by Js) can be established in advance based on multiple experiments, and this first mapping relationship can be stored in the vehicle's storage module.

[0140] For example, the first mapping relationship can be shown in Table 1 below: Table 1

[0141] As shown in Table 1 above, the third correction factor gradually increases as the vehicle speed increases.

[0142] Understandably, at low speeds, the vehicle's centrifugal force is extremely low, the tire side slip effect is almost negligible, and the center of gravity side slip angle is very small, which does not affect driving stability. At this time, the driving requirement is "small turning radius, agile and controllable." If the third correction coefficient is too large (strong rear-wheel steering correction), it may lead to oversteer, increasing the difficulty of low-speed handling. Therefore, at low speeds, the third correction coefficient can be taken to a minimum value (close to 0), retaining only a small correction amount to avoid mechanical shock and ensure agility and stability during low-speed steering.

[0143] As vehicle speed increases (30-80 km / h), centrifugal force increases with the square of vehicle speed, the tire slip angle begins to increase significantly, and the center of gravity slip angle gradually becomes more prominent, posing a risk of vehicle deviation from the steering trajectory. Therefore, the third correction coefficient can be gradually increased to make the rear wheels steer in coordination with the front wheels, offsetting part of the slip effect, avoiding lag or over-steering response, and making the steering trajectory more closely match the driver's input.

[0144] Table 1 above is only an example of the first mapping relationship between vehicle speed and the third correction coefficient. The specific content of the first mapping relationship is not specifically limited in the embodiments of this application.

[0145] Furthermore, after obtaining the current vehicle speed, the vehicle controller can query the first mapping relationship stored in the vehicle's storage module, determine the third correction coefficient (i.e., Js) corresponding to the current vehicle speed based on the first mapping relationship, and correct the initial proportional coefficient based on the third correction coefficient (i.e., Js) to obtain the target proportional coefficient.

[0146] Specifically, the target scaling factor = initial scaling factor * Js.

[0147] For example, assuming that the initial proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle is 0.5 calculated based on the above formula (12), if the current vehicle speed is 50km / h, by consulting Table 1 above, it can be determined that the third correction coefficient Js corresponding to the current vehicle speed is 0.5. Then, the third correction coefficient can be multiplied by the initial proportional coefficient to obtain the target proportional coefficient of 0.25.

[0148] In some embodiments, the third correction factor can also be set according to the user's actual needs. The user can adjust the third correction factor in the vehicle's custom settings module, and the vehicle's controller can directly correct the initial proportional coefficient based on the user-defined third correction factor.

[0149] For example, the vehicle can provide a custom settings module, through which the user can adjust the aforementioned third correction coefficient. For instance, a slider in the range of 0 to 1.0 (corresponding to the value range of the third correction coefficient) can be displayed on the vehicle's central control screen, with the current value displayed in real time on the slider (accurate to 0.01). The user can adjust the value of the third correction coefficient by sliding the slider.

[0150] To ensure vehicle safety, the user-adjusted values ​​can be verified. If the third correction factor after adjustment exceeds the safe range, the user will be notified, and the third correction factor will be locked within the safe range, terminating the user's custom adjustment.

[0151] Furthermore, after correcting the initial scaling factor based on the third correction factor, the target scaling factor can be specifically expressed as P*Js.

[0152] For example, assuming the initial scaling factor is corrected based on the third correction factor, the target scaling factor can be P*Js. Substituting this into the above formula (20), we can obtain the second relationship as follows: .

[0153] The above method, based on vehicle dynamics characteristic parameters and the first relational formula, calculates the initial proportional coefficient. It can establish a basic matching logic for the steering angles of the rear and front wheels based on the vehicle's own dynamic characteristics. By accurately matching the steering ratios of the front and rear wheels, it achieves a zero sideslip angle, thereby improving the vehicle's driving stability during steering. Determining the third correction coefficient corresponding to the current vehicle speed can accurately adapt to the dynamic impact of vehicle speed changes on the vehicle's steering dynamics, avoiding the imbalance of rear and front wheel steering coordination caused by speed fluctuations in the initial proportional coefficient, and ensuring the adaptability of steering coordination at different vehicle speeds. By correcting the initial proportional coefficient through the third correction coefficient associated with vehicle speed, it can effectively compensate for the steering coordination deviation caused by vehicle speed. Ultimately, it ensures that the ratio of the steering angles of the rear and front wheels always adapts to the current vehicle speed and vehicle dynamics, achieving coordination, stability, and flexibility in the vehicle's steering response across the entire speed range, and improving the driving experience and driving safety in different driving scenarios.

[0154] In steps 104 and 105, the initial front wheel steering angle refers to the initial angle calculated based on the current rotation angle of the steering wheel and the current transmission ratio of the front wheels.

[0155] For example, the initial front wheel steering angle mentioned above is specifically calculated using the following formula (21): Formula (21) In formula (21), the above Let be the initial front wheel steering angle of the vehicle, s be the steering wheel rotation angle, and i be the transmission ratio of the front wheels of the vehicle.

[0156] The aforementioned front wheel gear ratio refers to the nominal gear ratio of the front wheels in the steer-by-wire system (because the steer-by-wire system eliminates the mechanical connection between the steering wheel and the front wheels, this gear ratio is not a fixed value determined by the mechanical structure). This nominal gear ratio is a reference value (e.g., 1 / 15) set in the vehicle's control system before the vehicle leaves the factory, which the vehicle's controller can directly obtain. In the steer-by-wire system, the vehicle's controller dynamically adjusts the actual steering output based on real-time operating conditions, causing a deviation between the actual gear ratio and the nominal gear ratio.

[0157] In order to make the yaw rate gain of the vehicle when the four wheels are turning similar to that when the front wheels are turning, the initial front wheel steering angle can be corrected based on the first correction coefficient calculated above to obtain the target front wheel steering angle, and the vehicle can be controlled to turn the four wheels based on the target front wheel steering angle.

[0158] The aforementioned target front wheel steering angle refers to the front wheel steering angle that, after correcting the initial front wheel steering angle, enables the vehicle to achieve the same overall vehicle yaw rate gain in four-wheel steering mode as in front-wheel steering mode.

[0159] Specifically, by combining the above formulas (20) and (21), the corrected target front wheel steering angle can be obtained, which can be expressed by the following formula (22): Formula (22) In formula (22), the above Here, s is the target front wheel steering angle of the vehicle, i is the nominal transmission ratio of the front wheels of the vehicle, P is the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle, and Js is the third correction coefficient.

[0160] Understandably, yaw rate gain is essentially the ratio of yaw rate to front wheel steering angle. When four wheels are steering, because the rear wheels participate in the steering, their yaw rate gain (i.e., the first yaw rate gain) differs from the gain when the front wheels are steering (i.e., the second yaw rate gain). The target front wheel steering angle is obtained by dividing the initial front wheel steering angle by the ratio of the first yaw rate gain to the second yaw rate gain. Essentially, this is to make the target front wheel steering angle the reciprocal of the gain ratio of the two steering methods, thereby canceling out the gain difference between the two steering methods. Ultimately, the yaw rate gain when four wheels are steering returns to the level of the yaw rate gain when only the front wheels are steering, thus achieving consistency in the yaw rate gain of the two steering methods and ensuring the uniformity of the vehicle's steering response.

[0161] For example, assuming the third correction coefficient Js is 0.5, the target ratio coefficient P between the rear wheel steering angle and the front wheel steering angle of the vehicle is 0.5, the nominal transmission ratio i of the vehicle is steering wheel angle: front wheel angle = 15:1, and the current steering wheel rotation angle s is 150 degrees, substituting the above data into the above formula (22), we can obtain the target front wheel steering angle as 13.4 degrees, and then we can control the vehicle to perform four-wheel steering based on the target front wheel steering angle.

[0162] Furthermore, in order to adapt the corrected target front wheel steering angle to the actual driving conditions of the vehicle, in addition to correcting the initial front wheel steering angle based on the first correction coefficient mentioned above, the initial front wheel steering angle can also be corrected based on the current vehicle speed.

[0163] In some embodiments, before obtaining the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle, the method further includes: obtaining a second correction coefficient corresponding to the current vehicle speed; obtaining the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle includes: correcting the initial front wheel steering angle of the vehicle based on the first correction coefficient and the second correction coefficient to obtain the target front wheel steering angle.

[0164] It is understandable that the aforementioned second correction factor can be a scaling factor that varies with vehicle speed, and can be determined based on the current vehicle speed.

[0165] In some embodiments, obtaining a second correction coefficient corresponding to the vehicle's current speed includes: obtaining the vehicle's current speed; determining that the second correction coefficient is a value greater than 1 when the current speed is less than or equal to a preset speed; and determining that the second correction coefficient is a value less than 1 when the current speed is greater than the preset speed.

[0166] The aforementioned current vehicle speed typically refers to the vehicle's longitudinal speed (speed along the x-axis of the vehicle body), measured in kilometers per hour (km / h). Wheel speeds are usually detected by wheel speed sensors, and the vehicle's controller determines the current vehicle speed based on the measured wheel speeds.

[0167] For example, the preset vehicle speed can be set according to actual needs, such as 50 km / h. Specifically, the preset vehicle speed can be set by the user according to actual needs, or the vehicle can be set according to the user's driving preferences.

[0168] Furthermore, multiple experiments can be conducted in advance to establish a second mapping relationship between each vehicle speed and the second correction coefficient (represented by Ks) based on the experimental results, and this second mapping relationship can be stored in the vehicle's storage module.

[0169] For example, taking a preset vehicle speed of 50km / h as an example, the second mapping relationship can be shown in Table 2 below: Table 2

[0170] As shown in Table 2 above, when the current vehicle speed is less than the preset vehicle speed, the second correction coefficient is always a value greater than 1, and the second correction coefficient increases as the vehicle speed decreases; while when the current vehicle speed is greater than the preset vehicle speed, the second correction coefficient is always a value less than 1, and the second correction coefficient decreases as the vehicle speed increases.

[0171] Understandably, at low speeds, the centrifugal force of a vehicle is small, and the tire yaw effect is weak. The difference between the first yaw rate gain when the vehicle is performing four-wheel steering and the second yaw rate gain when the vehicle is performing front-wheel steering will increase as the vehicle speed decreases (the amplification effect of rear-wheel steering on steering response is more obvious). Therefore, the correction range of the initial front wheel steering angle can be further amplified to offset the excessive increase of the first yaw rate relative to the second yaw rate at low speeds, ensuring the controllability of the vehicle when steering at low speeds.

[0172] At high speeds, the centrifugal force of a vehicle is large, and the tire yaw effect is significant. The difference between the first yaw rate gain when the vehicle is performing four-wheel steering and the second yaw rate gain when the vehicle is performing front-wheel steering decreases as the vehicle speed increases (rear-wheel steering focuses more on stability correction, and its amplification effect on the gain is weakened). Therefore, the correction range of the initial front wheel steering angle can be further reduced to adapt to the change in the ratio between the first and second yaw rates at high speeds, preventing excessive correction that could lead to an overly fast steering response and ensuring the vehicle's driving stability at high speeds.

[0173] Table 2 above is only an example of a second mapping relationship between vehicle speed and the second correction coefficient. The specific content of the second mapping relationship is not specifically limited in the embodiments of this application.

[0174] Furthermore, after obtaining the current vehicle speed, the vehicle controller can look up the corresponding second correction coefficient in Table 2 above based on the current vehicle speed, and correct the initial front wheel steering angle based on the first correction coefficient and the second correction coefficient.

[0175] Specifically, based on the above formula (22), a second correction coefficient (i.e., Ks) is added to obtain the corrected target front wheel steering angle, which can be expressed by the following formula (23): Formula (23) In the above formula (23), the above Let be the target front wheel steering angle of the vehicle, s be the steering wheel angle, i be the nominal transmission ratio of the front wheels of the vehicle, P be the ratio between the rear wheel steering angle and the front wheel steering angle of the vehicle, Js be the third correction coefficient, and Ks be the second correction coefficient.

[0176] For example, assuming the third correction coefficient Js is 0.5, the target ratio coefficient P between the rear wheel steering angle and the front wheel steering angle of the vehicle is 0.5, the nominal transmission ratio i of the vehicle is steering wheel angle: front wheel angle = 15:1, the current steering wheel rotation angle s is 150 degrees, the preset vehicle speed is 50km / h, if the current vehicle speed is obtained as 70km / h, then the second correction coefficient Ks corresponding to the current vehicle speed is determined to be 0.8. Substituting the above data into the above formula (23), the target front wheel steering angle can be obtained as 10.7 degrees, and then the vehicle can be controlled to perform four-wheel steering based on the target front wheel steering angle.

[0177] The above method obtains a second correction coefficient corresponding to the current vehicle speed, which can accurately adapt to the dynamic impact of vehicle speed changes on the yaw rate gain. It avoids the limitation that a single first correction coefficient can only achieve consistent yaw rate gains for four-wheel steering and front-wheel steering at a fixed vehicle speed, ensuring that a stable gain matching basis can be established in different speed ranges. Based on the first and second correction coefficients, the initial front wheel steering angle is corrected. The first correction coefficient can offset the gain difference between four-wheel steering and front-wheel steering, ensuring the uniformity of steering response logic. The second correction coefficient can compensate for the gain difference caused by vehicle speed, thus taking into account both the handling flexibility and driving stability of the vehicle when performing four-wheel steering at different speeds.

[0178] Furthermore, in addition to ensuring that the yaw rate gain of the vehicle when the four wheels are turning is consistent with the yaw rate gain when the front wheels are turning, the current road conditions can also be taken into account, and the current vehicle yaw rate can be limited based on the current road conditions.

[0179] For example, considering the road surface adhesion coefficient, the yaw rate of a vehicle during steering can be calculated using the following formula (24): Formula (24) In the above formula (24), To account for the vehicle's yaw rate after considering the road surface adhesion coefficient, abs represents taking the absolute value of the value within the parentheses in formula (24). Let g be the coefficient of friction between the vehicle's tires and the road surface, and g be the acceleration due to gravity, approximately 9.8 m / s². 2 , This represents the vehicle's current speed.

[0180] For example, suppose the vehicle is currently on a dry asphalt road surface. =0.8, g=9.8m / s 2 The current vehicle speed is obtained as 60km / h≈16.67m / s. Substituting the above value into formula (24), the yaw rate is calculated. =0.47 rad / s.

[0181] Furthermore, during the actual driving process of the vehicle, when only the front wheels of the vehicle are turning, the final target yaw rate can be obtained based on the above formula (14) and the above formula (24).

[0182] Specifically, the target yaw rate when the vehicle is turning its front wheels can be calculated using the following formula (25): Formula (25) In the above formula (25), The target yaw rate when the vehicle is steering with its front wheels; The yaw rate of the whole vehicle after considering the road surface adhesion coefficient is calculated based on the above formula (24); abs means taking the absolute value of the value in parentheses; min means taking the smaller value of the value in parentheses; The first yaw rate of the vehicle when the front wheels are turned is calculated based on the above formula (14); sign(x) refers to a function that determines the sign of the value based on the numerical value; if the input number x is greater than 0, the output sign(x) = 1; if the input number x is equal to 0, the output sign(x) = 0; if the input number x is less than 0, the output sign(x) = -1.

[0183] For example, assume that the first yaw rate of the vehicle when the front wheels are steered is calculated based on the above formula (14). The yaw rate of the whole vehicle after considering the road surface adhesion coefficient is 0.5 rad / s, calculated based on the above formula (24). The value is 0.47 rad / s. Substituting this value into formula (25), we can obtain the target yaw rate when the vehicle is turning its front wheels. It is 0.47 rad / s.

[0184] During actual vehicle operation, when the vehicle is performing four-wheel steering, the final target yaw rate can be obtained based on the above formulas (16) and (24).

[0185] Specifically, the target yaw rate of the vehicle when performing four-wheel steering can be calculated using the following formula (26): Formula (26) In the above formula (26), The target yaw rate when the vehicle is performing four-wheel steering; The yaw rate of the whole vehicle after considering the road surface adhesion coefficient is calculated based on the above formula (24); abs means taking the absolute value of the value in parentheses; min means taking the smaller value of the value in parentheses; The second yaw rate of the vehicle when it performs four-wheel steering is calculated based on the above formula (16); sign(x) refers to a function that determines the sign of the value based on the numerical value; if the input number x is greater than 0, the output sign(x) = 1; if the input number x is equal to 0, the output sign(x) = 0; if the input number x is less than 0, the output sign(x) = -1.

[0186] For example, assume that the second yaw rate of the vehicle when performing four-wheel steering is calculated based on the above formula (16). The yaw rate of the vehicle after considering the road surface adhesion coefficient is 0.4 rad / s, calculated based on the above formula (24). The value is 0.47 rad / s. Substituting this value into formula (26), we can obtain the target yaw rate when the vehicle is turning its front wheels. It is 0.4 rad / s.

[0187] The above method, while ensuring that the yaw rate gain of the four-wheel steering and the front-wheel steering is consistent, dynamically calculates the safe upper limit of the yaw rate by combining the current road surface adhesion coefficient, and actively limits the yaw rate of the whole vehicle to not exceed the road surface friction limit. It can maintain sufficient handling flexibility on high-adhesion roads and intervene in anti-skid in advance on low-adhesion roads, thus achieving a balance between steering response consistency, handling and driving safety under different road conditions. This makes the vehicle more adaptable to complex road conditions and further improves the vehicle's steering performance.

[0188] Figure 3 This is a schematic diagram of a steering control device provided in an embodiment of this application.

[0189] For example, such as Figure 3 As shown, the device 300 includes: The acquisition module 301 is used to acquire dynamic characteristic parameters related to vehicle steering.

[0190] The first generation module 302 is used to obtain the target proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on the dynamic characteristic parameters and the first relation.

[0191] The first relationship is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero.

[0192] The determination module 303 is used to determine the first correction coefficient based on the target proportional coefficient and the second relationship.

[0193] The second relationship is used to characterize the degree of difference between the yaw rate gains when the vehicle is steering in different steering methods.

[0194] The second generation module 304 is used to obtain the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle.

[0195] The control module 305 is used to control the vehicle to perform four-wheel steering based on the target front wheel steering angle.

[0196] In some embodiments, the device further includes a second acquisition module, which is configured to: acquire a second correction coefficient corresponding to the current vehicle speed; and the second generation module is specifically configured to: correct the initial front wheel steering angle of the vehicle based on the first correction coefficient and the second correction coefficient to obtain a target front wheel steering angle.

[0197] In some embodiments, the first generation module is specifically used to: obtain the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase; calculate the vehicle's front wheel steering angle based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, and the vehicle's wheelbase; calculate the vehicle's rear wheel steering angle based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase; and determine the ratio between the rear wheel steering angle and the front wheel steering angle as a target proportionality coefficient.

[0198] In some embodiments, the second relation is represented as the difference between a preset value and the first relation, and the first correction coefficient is determined based on the difference between the preset value and the target proportional coefficient.

[0199] In some embodiments, the device includes a third acquisition module, which is specifically configured to: acquire a first yaw rate gain when the vehicle is performing front wheel steering, a second yaw rate gain when the vehicle is performing four-wheel steering, and a first relational expression; and obtain a second relational expression based on the first yaw rate gain, the second yaw rate gain, and the first relational expression.

[0200] In some embodiments, the device further includes a fourth acquisition module, which is specifically used for: acquiring a two-degree-of-freedom vehicle dynamics model; replacing the lateral force of the front tires in the two-degree-of-freedom vehicle dynamics model with the product of the front axle side slip stiffness and the front wheel side slip angle, and replacing the lateral force of the rear tires in the two-degree-of-freedom vehicle dynamics model with the product of the rear axle side slip stiffness and the rear wheel side slip angle, to obtain a third relational expression after rewriting the two-degree-of-freedom vehicle dynamics model; replacing the front wheel side slip angle in the third relational expression with an expression related to the front wheel steering angle, and replacing the rear wheel side slip angle in the third relational expression with an expression related to the rear wheel steering angle, to obtain a fourth relational expression after rewriting the third relational expression; and obtaining a first relational expression based on the fourth relational expression and preset constraints; wherein the preset constraint is that the vehicle's center of gravity side slip angle is equal to zero.

[0201] In some embodiments, the first generation module is specifically used to: calculate an initial proportional coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on dynamic characteristic parameters and a first relational formula; determine a third correction coefficient corresponding to the current vehicle speed; and correct the initial proportional coefficient based on the third correction coefficient to obtain a target proportional coefficient.

[0202] In some embodiments, the second acquisition module is specifically used to: acquire the current vehicle speed; determine a second correction coefficient greater than 1 if the current vehicle speed is less than or equal to a preset vehicle speed; and determine a second correction coefficient less than 1 if the current vehicle speed is greater than the preset vehicle speed.

[0203] Figure 4 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application.

[0204] For example, such as Figure 4 As shown, the vehicle 400 includes a memory 401 and a processor 402. The memory 401 stores executable program code 4011, and the processor 402 is used to call and execute the executable program code 4011 to perform a steering control method.

[0205] Furthermore, embodiments of this application also protect an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a steering control method provided in embodiments of this application.

[0206] This embodiment can divide the device into functional modules based on the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0207] When each functional module is divided according to its corresponding function, the device may further include an acquisition module, a first generation module, a determination module, a second generation module, and a control module. It should be noted that all relevant content regarding the steps involved in the above method embodiments can be referenced to the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0208] It should be understood that the device provided in this embodiment is used to execute the steering control method described above, and therefore can achieve the same effect as the implementation method described above.

[0209] When using an integrated unit, the device may include a processing module and a storage module. When the device is applied to a vehicle, the processing module can be used to control and manage the vehicle's movements. The storage module can be used to support the vehicle in executing relevant program code and data.

[0210] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits shown in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0211] In addition, the device provided in the embodiments of this application may specifically be a chip, component or module. The chip may include a connected processor and a memory. The memory is used to store instructions. When the processor calls and executes the instructions, the chip can execute a steering control method provided in the above embodiments.

[0212] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the aforementioned method steps to implement a steering control method provided in the above embodiment.

[0213] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned steps to implement a steering control method provided in the above embodiment.

[0214] In this embodiment, the device, computer-readable storage medium, computer program product, or chip are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0215] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0216] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0217] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A steering control method, characterized in that, The method includes: Obtain dynamic characteristic parameters related to vehicle steering; Based on the dynamic characteristic parameters and the first relationship, the target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle is obtained; wherein, the first relationship is the proportional relationship between the rear wheel steering angle and the front wheel steering angle when the vehicle's center of gravity sideslip angle is zero. Based on the target proportional coefficient and the second relationship, a first correction coefficient is determined; wherein, the second relationship is used to characterize the degree of difference between the yaw rate gains when the vehicle turns in different steering methods; Based on the first correction coefficient and the initial front wheel steering angle of the vehicle, the target front wheel steering angle is obtained; The vehicle is controlled to perform four-wheel steering based on the target front wheel steering angle.

2. The method according to claim 1, characterized in that, Before obtaining the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle, the method further includes: Obtain the second correction coefficient corresponding to the current speed of the vehicle; The process of obtaining the target front wheel steering angle based on the first correction coefficient and the initial front wheel steering angle of the vehicle includes: Based on the first correction coefficient and the second correction coefficient, the initial front wheel steering angle of the vehicle is corrected to obtain the target front wheel steering angle.

3. The method according to claim 1, characterized in that, The step of obtaining the target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on the dynamic characteristic parameters and the first relationship includes: The vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, the vehicle's rear axle lateral stiffness, and the vehicle's wheelbase are obtained. The front wheel steering angle of the vehicle is calculated based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the vehicle's front axle lateral stiffness, and the vehicle's wheelbase. The rear wheel steering angle of the vehicle is calculated based on the vehicle's current speed, the distance from the vehicle's center of gravity to the front axle, the distance from the vehicle's center of gravity to the rear axle, the vehicle's mass, the rear axle lateral stiffness, and the vehicle's wheelbase. The ratio between the rear wheel steering angle and the front wheel steering angle is determined as the target proportional coefficient.

4. The method according to claim 1, characterized in that, The second relation is expressed as the difference between the preset value and the first relation, and the first correction coefficient is determined based on the difference between the preset value and the target proportional coefficient.

5. The method according to claim 1 or 4, characterized in that, The second relation is generated in the following way: Obtain the first yaw rate gain when the vehicle performs front wheel steering, the second yaw rate gain when the vehicle performs four-wheel steering, and the first relationship; Based on the first yaw rate gain, the second yaw rate gain, and the first relational expression, the second relational expression is obtained.

6. The method according to claim 1 or 3, characterized in that, The first relation is generated in the following way: Obtain a two-degree-of-freedom vehicle dynamics model; The lateral force of the front tire in the two-degree-of-freedom vehicle dynamics model is replaced by the product of the front axle lateral stiffness and the front wheel slip angle, and the lateral force of the rear tire in the two-degree-of-freedom vehicle dynamics model is replaced by the product of the rear axle lateral stiffness and the rear wheel slip angle, resulting in the third relational expression after rewriting the two-degree-of-freedom vehicle dynamics model. The front wheel slip angle in the third relation is replaced with an expression related to the front wheel steering angle, and the rear wheel slip angle in the third relation is replaced with an expression related to the rear wheel steering angle, resulting in a fourth relation after rewriting the third relation. Based on the fourth relation and the preset constraint, the first relation is obtained; wherein, the preset constraint is that the vehicle's center of gravity sideslip angle is equal to zero.

7. The method according to claim 1, characterized in that, The step of obtaining the target proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle based on the dynamic characteristic parameters and the first relationship includes: Based on the dynamic characteristic parameters and the first relationship, the initial proportionality coefficient between the rear wheel steering angle and the front wheel steering angle of the vehicle is calculated. Determine a third correction factor corresponding to the current speed of the vehicle; The initial scaling factor is corrected based on the third correction factor to obtain the target scaling factor.

8. The method according to claim 2, characterized in that, The step of obtaining the second correction coefficient corresponding to the current vehicle speed includes: Obtain the current speed of the vehicle; If the current vehicle speed is less than or equal to the preset vehicle speed, the second correction coefficient is determined to be a value greater than 1. If the current vehicle speed is greater than the preset vehicle speed, the second correction coefficient is determined to be a value less than 1.

9. A vehicle, characterized in that, The vehicles include: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method as described in any one of claims 1 to 8.

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