A vehicle control method for an open road surface and related apparatus

Abstract

The application provides a vehicle control method for a split road surface and a related device, and relates to the technical field of automobile control. When it is determined that the vehicle is on a split road surface, the adhesion coefficient of the low adhesion side and the actual acceleration of the vehicle are calculated, then the yaw moment of the vehicle is calculated based on the adhesion coefficient and the actual acceleration, the required turning angle of the rear wheel is further calculated based on the yaw moment and the rear wheel side stiffness, the expected yaw angular velocity and the actual yaw angular velocity of the vehicle are obtained, PID control is performed based on the expected yaw angular velocity and the actual yaw angular velocity, the turning angle of the rear wheel is obtained, the turning angle instruction of the final angle of the rear wheel steering is generated based on the required turning angle of the rear wheel and the turning angle of the rear wheel, and the turning angle instruction is sent to the rear wheel steering actuator, so that the vehicle can still keep straight driving when the vehicle is on a split road surface.

Description

Technical Field

[0001] This invention relates to the field of automotive control technology, and more specifically to a vehicle control method and related device for a split-road vehicle. Background Technology

[0002] A split-type road surface refers to a road surface where one side has a high coefficient of adhesion and the other side has a low coefficient of adhesion. This type of road surface is often used to verify whether the road surface recognition method for wheels on the left and right sides of the same axle is affected by the other side of the wheel.

[0003] Furthermore, when driving on split-road surfaces, the different coefficients of adhesion between the left and right wheels often generate significant yaw moments during emergency braking, causing the vehicle to deviate from its intended direction and potentially leading to instability such as skidding, veering, and fishtailing. Therefore, split-road testing is crucial for evaluating a vehicle's stability and safety. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a vehicle control method and related apparatus for split-road surfaces.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A vehicle control method for split-road surfaces, comprising:

[0007] Determine if the vehicle is on the opposite side of the road;

[0008] When the vehicle is on a split road surface, calculate the adhesion coefficient on the side with lower adhesion.

[0009] Obtain the vehicle's actual acceleration;

[0010] The yaw moment of the vehicle is calculated based on the adhesion coefficient and the actual acceleration.

[0011] The required rear wheel steering angle is calculated based on the yaw moment and rear wheel lateral stiffness.

[0012] Obtain the vehicle's desired yaw rate;

[0013] Obtain the vehicle's actual yaw rate;

[0014] PID control is performed based on the desired yaw rate and the actual yaw rate to obtain the rear wheel steering angle;

[0015] Based on the required rear wheel steering angle and the rear wheel steering angle, a steering angle command is generated for the final steering angle of the rear wheels, and the steering angle command is sent to the rear wheel steering actuator.

[0016] Optionally, in the above-mentioned vehicle control method for split-level roads, determining whether a vehicle is located on a split-level road includes:

[0017] The slip ratios of the wheels on both sides of the vehicle are obtained. When the slip ratio of at least one wheel on either side is higher than a preset slip ratio threshold, and the slip ratios of the wheels on the other side are all lower than the preset slip ratio threshold, the vehicle is determined to be on a split road surface. Otherwise, the vehicle is determined not to be on a split road surface.

[0018] Optionally, in the above-mentioned vehicle control method for split-road surfaces, after determining that the vehicle is on a split-road surface and before calculating the adhesion coefficient of the low-adhesion side, the method further includes:

[0019] Determine if the user intends to keep the vehicle moving straight. If the user intends to keep the vehicle moving straight, activate the active control of the rear wheel steering and continue with the following steps: calculate the adhesion coefficient of the low-adhesion side and follow up with the next steps.

[0020] Optionally, in the above-mentioned vehicle control method for split-road surfaces, determining whether the user intends to keep the vehicle traveling straight includes:

[0021] When the vehicle is in driving mode, it is determined whether the user turns the steering wheel toward the side with higher traction on the opposite side of the road, and whether the turning angle is greater than a first preset angle; if the user turns the steering wheel toward the side with higher traction on the opposite side of the road, and the turning angle is greater than the first preset angle, it is determined that the user has the intention to keep the vehicle moving straight.

[0022] When the vehicle is braking, it is determined whether the user turns the steering wheel toward the side of the opposite road with low traction and whether the turning angle is greater than the second preset angle; if the user turns the steering wheel toward the side of the opposite road with low traction and the turning angle is greater than the second preset angle, it is determined that the user has the intention to keep the vehicle moving straight.

[0023] Optionally, in the above-described vehicle control method for split-road surfaces, obtaining the desired yaw rate of the vehicle includes:

[0024] Based on the steering wheel angle and vehicle speed, the desired yaw rate of the vehicle is calculated using a two-degree-of-freedom vehicle model.

[0025] Optionally, the above-mentioned vehicle control method for split-road surfaces further includes: determining whether the vehicle's ABS or TCS function is activated; if the ABS or TCS function is activated, performing steps to calculate the adhesion coefficient of the low-adhesion side and subsequent steps until the steering angle command is sent to the rear wheel steering actuator.

[0026] A vehicle control device for split-road surfaces, comprising:

[0027] The first judgment unit is used to determine whether the vehicle is located on the opposite road surface;

[0028] The adhesion coefficient calculation unit is used to calculate the adhesion coefficient of the low-adhesion side when the vehicle is on a split road surface.

[0029] The vehicle speed acquisition unit is used to obtain the actual acceleration of the vehicle;

[0030] A yaw moment calculation unit is used to calculate the yaw moment of the vehicle based on the adhesion coefficient and the actual acceleration.

[0031] The required steering angle calculation unit is used to calculate the required steering angle of the rear wheel based on the yaw moment and the rear wheel lateral stiffness.

[0032] The PID control unit is used to obtain the desired yaw rate of the vehicle, obtain the actual yaw rate of the vehicle, perform PID control based on the desired yaw rate and the actual yaw rate, and calculate the rear wheel steering angle.

[0033] The instruction sending unit is used to generate a steering angle instruction for the final steering angle of the rear wheels based on the required rear wheel steering angle and the rear wheel steering angle, and send the steering angle instruction to the rear wheel steering actuator.

[0034] A computer program product includes computer-readable instructions that, when executed on an electronic device, cause the electronic device to implement the vehicle control method for split-road surfaces as described above.

[0035] An electronic device includes at least one processing device and a storage device connected to the processing device, wherein:

[0036] The storage device is used to store computer programs;

[0037] The processing device is used to execute the computer program so that the electronic device can implement the vehicle control method for split-road surfaces as described in any of the above-described methods.

[0038] A computer storage medium carrying one or more computer programs, which, when executed by an electronic device, enable the electronic device to implement the vehicle control method for split-road surfaces described above.

[0039] Based on the above technical solution, the solution provided by the embodiments of the present invention, when it is determined that the vehicle is on a split road surface, calculates the adhesion coefficient of the low adhesion side and the actual acceleration of the vehicle, then calculates the yaw moment of the vehicle based on the adhesion coefficient and the actual acceleration, and further calculates the required rear wheel steering angle based on the yaw moment and the rear wheel lateral stiffness, obtains the desired yaw rate and the actual yaw rate of the vehicle, and then performs PID control based on the desired yaw rate and the actual yaw rate to obtain the rear wheel steering angle. Based on the required rear wheel steering angle and the rear wheel steering angle, a steering angle command of the final rear wheel steering angle is generated and sent to the rear wheel steering actuator, thereby ensuring that the vehicle can still maintain straight-line travel when on a split road surface. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0041] Figure 1 A schematic diagram of the terminal for applying the vehicle control method on split-road surfaces;

[0042] Figure 2 This is a schematic diagram of the vehicle control method for split-road surfaces disclosed in an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of the structure of a vehicle control device for a publicly accessible split road surface according to an embodiment of this application;

[0044] Figure 4 This is a schematic diagram of the structure of the electronic device disclosed in the embodiments of this application. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Among existing vehicles, some are not equipped with rear-wheel steering, while others are. The applicant's research has revealed that vehicles without rear-wheel steering require constant steering wheel adjustments by the driver to prevent them from veering off course when driving on parallel roads. Vehicles equipped with rear-wheel steering, however, can actively control the rear wheel steering to maintain a straight course on parallel roads, reducing driver intervention. Therefore, this invention addresses vehicles equipped with rear-wheel steering by implementing an active rear-wheel steering control algorithm in the controller, thereby improving the vehicle's stability, convenience, power, and braking performance when driving on parallel roads.

[0047] The vehicle control method for bi-lane roads designed in this invention, through bi-lane road recognition, theoretical feedforward calculation, and closed-loop feedback control, enables the vehicle to maintain straight-line travel while reducing driver steering wheel intervention on bi-lane roads. Furthermore, by using more aggressive TCS calibration parameters, the vehicle's acceleration performance on bi-lane roads can be improved. Similarly, by using more aggressive ABS calibration parameters, the braking distance on bi-lane roads can be shortened, demonstrating certain application value and reference significance.

[0048] See Figure 1 , Figure 1 A schematic diagram of a terminal for implementing a vehicle control method for split-road surfaces is shown. The terminal 100 can receive various relevant parameters used in the process of executing the vehicle control method for split-road surfaces, and then execute the relevant steps of the vehicle control method for split-road surfaces based on these parameters.

[0049] The following description Figure 1 The product form of the mid-terminal 100;

[0050] The terminal 100 in this application embodiment can be a vehicle computer or other data processing device installed in the vehicle, and this application embodiment does not impose any restrictions on it.

[0051] Figure 1 A schematic diagram of an optional hardware structure for terminal 100 is shown.

[0052] refer to Figure 1 As shown, the terminal 100 may include a radio frequency unit 110, a memory 120, an input unit 130, a display unit 140, a camera 150 (optional), an audio circuit 160 (optional), a speaker 161 (optional), a microphone 162 (optional), a headphone jack 163 (optional), a processor 170, an external interface 180, a power supply 190, and other components. Those skilled in the art will understand that... Figure 1 These are merely examples of terminals or multi-functional devices and do not constitute a limitation on terminals or multi-functional devices. They may include more or fewer components than shown in the illustration, or combine certain components, or use different components.

[0053] The input unit 130 can be used to receive relevant configuration instructions input by the user. Specifically, the input unit 130 may include a touch screen 131 (optional) and / or other input devices 132. The touch screen 131 can collect touch operations performed by the user on or near it (such as operations performed by the user using fingers, knuckles, styluses, or any suitable object on or near the touch screen) and drive the corresponding connection device according to a pre-set program. The touch screen can detect the user's touch action, convert the touch action into a touch signal and send it to the processor 170, and can receive and execute commands sent by the processor 170; the touch signal includes at least touch point coordinate information. The touch screen 131 can provide an input interface and an output interface between the terminal 100 and the user. In addition, various types of touch screens, such as resistive, capacitive, infrared, and surface acoustic wave, can be used to implement the touch screen. In addition to the touch screen 131, the input unit 130 may also include other input devices. Specifically, other input devices 132 may include, but are not limited to, one or more of the following: physical keyboard, function keys (such as volume control buttons, power buttons, etc.), trackball, mouse, joystick, etc. The input device 132 can receive input data generated based on user operations, etc.

[0054] The display unit 140 can be used to display information input by the user or information provided to the user, various menus of the terminal 100, interactive interfaces, file display, and / or playback of any multimedia file. In this embodiment, the display unit 140 can be used to display whether the vehicle is on a split road surface, and a scene diagram of vehicles on a split road surface. In this scene diagram, the adhesion coefficient of each tire of the vehicle can be displayed by means of simulated images, and the tires in a low adhesion state are marked.

[0055] The memory 120 can be used to store instructions and data. The memory 120 may primarily include an instruction storage area and a data storage area. The data storage area can store various types of data, such as multimedia files and text. The instruction storage area can store software units such as operating systems, applications, and instructions required for at least one function, or subsets or extended sets thereof. It may also include non-volatile random access memory. It provides the processor 170 with hardware, software, and data resources for managing the computing device, supporting control software and applications. It is also used for storing multimedia files, as well as storing running programs and applications.

[0056] The processor 170 is the control center of the terminal 100. It connects various parts of the terminal 100 via various interfaces and lines. By running or executing instructions stored in the memory 120 and calling data stored in the memory 120, it performs various functions of the terminal 100 and processes data, thereby controlling the terminal device as a whole. Optionally, the processor 170 may include one or more processing units; preferably, the processor 170 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, user interface, and applications, and the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 170. In some embodiments, the processor and memory can be implemented on a single chip; in some embodiments, they can also be implemented separately on independent chips. The processor 170 can also be used to generate corresponding operation control signals, send them to the corresponding components of the computing processing device, read and process data in the software, especially read and process data and programs in the memory 120, so that the various functional modules therein perform corresponding functions, thereby controlling the corresponding components to act according to the instructions.

[0057] The memory 120 can be used to store software code related to the vehicle control method for split-road surfaces, and the processor 170 can execute the various steps of the vehicle control method for split-road surfaces, and can also schedule other units (such as the above-mentioned input unit 130 and display unit 140) to achieve the corresponding functions.

[0058] The radio frequency unit 110 (optional) can be used for receiving and transmitting information, for example, receiving downlink information from the base station and processing it by the processor 170; and sending uplink data to the base station. Typically, the RF circuit includes, but is not limited to, an antenna, at least one amplifier, a transceiver, a coupler, a low-noise amplifier (LNA), a duplexer, etc. Furthermore, the radio frequency unit 110 can also communicate wirelessly with network devices and other devices. This wireless communication can use any communication standard or protocol, including but not limited to Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), email, Short Messaging Service (SMS), etc.

[0059] For details, see Figure 2 The vehicle control method for split-road surfaces disclosed in this application includes:

[0060] Step S201: Determine whether the vehicle is located on the opposite side of the road.

[0061] Split-road surfaces refer to road conditions where the two sides have different coefficients of adhesion. One side of the road has a high coefficient of adhesion (such as a dry, hard road surface), while the other side has a low coefficient of adhesion (such as a wet, muddy, or snow-covered road surface). These road conditions often cause yaw moments in vehicles during driving, thus affecting vehicle stability and safety.

[0062] The vehicle system can determine the adhesion coefficient of each wheel based on the slipping state (slip ratio) of the four wheels. For example, when the slip ratio of a certain wheel exceeds a certain threshold, it is determined that the wheel is on a low-adhesion surface.

[0063] In a specific scenario, when either of the two wheels on the left side of the vehicle is on a low-adhesion (low coefficient of adhesion) road surface, and both wheels on the right side are on a high-adhesion (high coefficient of adhesion) road surface, and the lateral acceleration of the vehicle is less than a certain threshold, then the Base condition of the split road surface with low adhesion on the left and high adhesion on the right is met. At this time, it is determined that the vehicle is on a split road surface with low adhesion on the left and high adhesion on the right.

[0064] In a specific scenario, when either of the two right wheels is on a low-adhesion surface and both left wheels are on a high-adhesion surface, and the lateral acceleration is less than a certain threshold, the Base condition of the split-road surface with high adhesion on the left and low adhesion on the right is met. At this time, it is determined that the vehicle is on a split-road surface with high adhesion on the left and low adhesion on the right (high adhesion coefficient on the left and low adhesion coefficient on the right).

[0065] The slip ratio of each wheel of a vehicle can be calculated in the following way:

[0066] Calculations based on vehicle speed and wheel speed:

[0067] Formula: Slip ratio S = [(V - ωr) / V] × 100%, where V represents the vehicle speed, i.e. the speed at which the vehicle travels on the ground; ω represents the rolling angular velocity of the wheel; and r represents the wheel radius.

[0068] step:

[0069] First, the vehicle speed V is obtained through the vehicle speed sensor.

[0070] Then, the wheel rolling angular velocity ω is obtained through the wheel speed sensor.

[0071] Next, measure or obtain the wheel radius r.

[0072] Finally, substitute the above data into the formula to calculate the slip ratio.

[0073] Calculations based on wheel center velocity and wheel angular velocity:

[0074] Formula: Slip ratio S = [(UW - rro ωW) / UW] × 100%, where UW represents the wheel center velocity; rro represents the wheel rolling radius when there is no ground braking force; ωW represents the wheel angular velocity.

[0075] step:

[0076] The wheel center velocity UW and wheel angular velocity ωW are obtained through corresponding sensors.

[0077] Measure or obtain the wheel rolling radius rro when there is no ground braking force.

[0078] Substitute the above data into the formula to calculate the slip ratio.

[0079] Calculations based on the car's theoretical speed and actual speed:

[0080] Formula: Slip ratio δ = [(Vt - Va) / Vt] × 100%, where Vt represents the theoretical speed of the car; Va represents the actual speed of the car.

[0081] step:

[0082] The theoretical speed Vt of the car is obtained through vehicle speed sensors or navigation systems.

[0083] The actual speed Va of the car is calculated using wheel speed sensors and vehicle speed sensors.

[0084] Substitute the above data into the formula to calculate the slip ratio.

[0085] Based on the slip ratio of each wheel, it is possible to determine whether the road surface corresponding to each wheel is a high-friction coefficient road surface or a low-friction coefficient road surface, and thus determine whether the vehicle is on a road surface with opposing sides.

[0086] Step S202: When the vehicle is on the opposite road surface, calculate the adhesion coefficient of the low adhesion side.

[0087] A higher slip ratio for a wheel indicates a lower coefficient of adhesion to the road surface corresponding to that wheel, and vice versa. Based on the slip ratio of each wheel, the coefficient of adhesion of the road surface corresponding to that wheel can be mapped, and then based on this value, it can be determined whether each wheel of the vehicle is on a road surface with a high coefficient of adhesion or a low coefficient of adhesion.

[0088] In addition to calculating the adhesion coefficient using the methods described above, the low-side adhesion coefficient can also be calculated during the vehicle's slippage window, based on the motor drive torque and the low-side rotational inertia torque, before the traction control system (TCS) intervenes. Specifically, this process may include:

[0089] Determine the slippage status:

[0090] First, it's necessary to determine if the vehicle is slipping. This is typically done by monitoring parameters such as wheel speed and slip ratio. Slip ratio is an important indicator, representing the degree of wheel slippage relative to the ground. When the slip ratio exceeds a certain threshold, the vehicle can be considered to be slipping.

[0091] Measure the motor drive torque:

[0092] When the vehicle is slipping, it is necessary to measure the drive torque output by the motor. This is typically achieved through a motor controller or sensors. The motor drive torque is one of the sources of power for the vehicle to move forward, and its magnitude directly affects the interaction force between the wheels and the ground.

[0093] Calculate the lower-side rotational inertia torque:

[0094] Low-friction side rotational inertial torque refers to the inertial torque generated by the rotation of the wheels when a vehicle is traveling on a surface with a low coefficient of friction. The magnitude of this torque is related to factors such as the wheel's mass, moment of inertia, and angular acceleration. In a slipping state, the low-friction side rotational inertial torque may increase because the wheel needs to overcome greater resistance to continue rotating.

[0095] Establish a dynamic model:

[0096] To calculate the low-side adhesion coefficient, a vehicle dynamics model needs to be established. This model should include parameters such as the vehicle's mass, tire mechanical properties, and the road surface adhesion coefficient. Using this model, the vehicle's motion under slippage conditions can be simulated, and the required adhesion coefficient can be calculated.

[0097] Solve for the low-side adhesion coefficient:

[0098] After establishing the dynamic model, the low-attached side adhesion coefficient can be solved using the known motor drive torque and low-attached side rotational inertia torque.

[0099] Step S203: Obtain the actual acceleration of the vehicle.

[0100] When calculating the actual acceleration of a vehicle, the actual acceleration of the vehicle can be measured by an accelerometer or an IMU (inertial measurement unit).

[0101] Step S204: Calculate the yaw moment of the vehicle based on the adhesion coefficient and the actual acceleration.

[0102] This step is used to calculate the yaw moment caused by the longitudinal force, based on the actual acceleration and the adhesion coefficient of the low-attachment side.

[0103] Specifically, to calculate the yaw moment caused by longitudinal forces that leads to vehicle deflection, it is necessary to consider the vehicle's tire characteristics, acceleration, and the coefficient of friction between the tires and the ground. The following is a simplified calculation process:

[0104] First, define the variables:

[0105] Fx: Longitudinal force (e.g., force generated by the engine or braking force).

[0106] ax: longitudinal acceleration

[0107] μ: Low side adhesion coefficient (i.e., the coefficient of friction between the tire and the ground)

[0108] h: Vehicle center of gravity height

[0109] d: The distance between the left and right tires of the vehicle (track width)

[0110] Mz: Yaw moment

[0111] Calculating longitudinal force: Generally, the longitudinal force Fx can be calculated using Newton's second law, i.e., Fx = m⋅ax, where m is the mass of the vehicle.

[0112] Considering tire characteristics: On low-traction surfaces, the longitudinal force on the tire is limited by the coefficient of adhesion. That is, Fx ≤ μ⋅Fz, where Fz is the vertical load on the tire. However, to simplify the calculation, we can assume that the tire is not saturated, i.e., Fx = mA⋅ax still holds.

[0113] Calculating yaw moment: When a vehicle accelerates or decelerates, due to the shift in the center of gravity (usually not on the vehicle's geometric center line), a moment is generated that causes the vehicle to rotate about its vertical axis (z-axis), i.e., yaw moment. This yaw moment can be calculated using the following formula: Mz = Fx⋅h⋅2d⋅sign(ax), where sign(ax) is a sign function of ax. When ax is positive (acceleration), sign(ax) = 1; when ax is negative (deceleration), sign(ax) = −1. Here, h⋅2d is a simplified representation of the horizontal distance from the center of gravity to the center of the tire; in reality, this distance may vary depending on the vehicle design.

[0114] Step S205: Calculate the required steering angle of the rear wheel based on the yaw moment and the rear wheel lateral stiffness.

[0115] To calculate the required rear wheel steering angle based on the offset yaw moment and rear wheel lateral stiffness, a vehicle dynamics model is required. Here, we assume the vehicle is a two-degree-of-freedom system, considering only yaw and lateral motion.

[0116] Define variables:

[0117] Mz: Offset yaw moment

[0118] K rear Rear wheel lateral stiffness

[0119] a: Distance from the vehicle's center of gravity to the front axle

[0120] b: Distance from the vehicle's center of gravity to the rear axle

[0121] Iz: Moment of inertia of the vehicle about the z-axis

[0122] δ rear Rear wheel steering angle requirement

[0123] Establishing the yaw motion equation: The yaw motion equation of a vehicle can typically be expressed as:

[0124] , where ω z β is the yaw rate, β is the sideslip angle, and K is the yaw rate. fLet be the front wheel sideslip stiffness, and u be the vehicle speed. However, to simplify the calculation and focus on the rear wheel steering angle, we can assume that the rates of change of the sideslip angle and yaw rate are small, thus neglecting the terms associated with them. Furthermore, if we are primarily concerned with the response of the rear wheel steering angle to the yaw moment, the equations can be further simplified.

[0125] Simplifying the equations and solving for the rear wheel steering angle: In the simplified case, the yaw motion equation can be approximated as: Here, we assume that the front wheel steering angle is very small or zero, and we mainly focus on the contribution of the rear wheel steering angle to the yaw moment.

[0126] Solving this equation, we get: Using this formula, the required rear wheel steering angle can be calculated based on the yaw moment and the rear wheel lateral stiffness.

[0127] Step S206: Obtain the desired yaw rate of the vehicle.

[0128] The desired yaw rate of a vehicle is an important vehicle dynamics parameter, commonly used in vehicle stability control and advanced driver assistance systems (ADAS). This application provides a method for obtaining the desired yaw rate of a vehicle using the following centralized approach:

[0129] I. Calculation based on vehicle dynamics model

[0130] Two-DOF vehicle model: In a two-DOF vehicle model, the desired yaw rate can be calculated using the vehicle's speed, steering angle, and physical parameters (such as mass, distance from the front and rear axles to the center of mass, tire lateral stiffness, etc.). The specific calculation formula may vary depending on the specific form of the model, but it usually involves a combination of vehicle speed, steering angle, and vehicle physical parameters.

[0131] II. Sensor-based Measurement and Estimation

[0132] Yaw-G sensor: The Yaw-G sensor (also known as a yaw rate sensor) can directly measure the yaw rate of a vehicle. This sensor is usually installed near the vehicle's center of gravity and detects the vehicle's yaw rate through the principle of inertial measurement.

[0133] Wheel speed difference estimation: When a vehicle is traveling in a curve, the outer wheels of the front and rear wheels usually rotate at a higher speed than the inner wheels. By measuring the difference in wheel speeds and combining it with parameters such as wheel angle and track width, the yaw rate of the vehicle can be estimated.

[0134] Lateral acceleration-vehicle speed method: By measuring the lateral acceleration and vehicle speed of a vehicle, the yaw rate of the vehicle can also be estimated.

[0135] III. Requirements Based on Control Algorithms

[0136] PID Control: In vehicle stability control systems, the PID control algorithm is often used to control the vehicle's yaw rate. By comparing the actual yaw rate with the desired yaw rate, an error signal is calculated, and the PID controller outputs control commands to adjust the vehicle's yaw rate.

[0137] LQR Algorithm: The LQR algorithm (Linear Quadratic Regulator) is also a commonly used control algorithm. It can calculate the appropriate control input based on the vehicle's dynamic equations and the desired yaw rate. In four-wheel independent drive vehicles, the LQR algorithm can achieve yaw rate tracking control.

[0138] In one specific embodiment of this application, the desired yaw rate can be calculated in the following way:

[0139] Based on a two-degree-of-freedom vehicle model, the desired yaw rate (rdes) is typically related to the steering wheel angle (δ) and vehicle speed (u). The two-degree-of-freedom model mainly considers the vehicle's yaw and roll motions (but in simplified models, roll motion is often ignored), and assumes that the vehicle only moves along the x-axis and that the tire slip characteristics are within a linear range.

[0140] For a two-degree-of-freedom model, the general expression for the desired yaw rate can be expressed as:

[0141] ,in:

[0142] u is the vehicle speed (m / s).

[0143] δ is the steering wheel angle (rad).

[0144] L is the wheelbase (m) of the vehicle, which is the distance from the front axle to the rear axle.

[0145] K is a stability factor, which is related to factors such as the vehicle's tire lateral stiffness, vehicle mass, and the distance from the front and rear axles to the center of gravity. For a given vehicle, K is a constant, but it needs to be determined through experiments or detailed vehicle parameters.

[0146] v is another representation of vehicle speed (usually the same as u, but v is retained in this formula to show the form of the original formula; in practical applications, it should be replaced with u).

[0147] After obtaining the steering wheel angle and vehicle speed, substitute these parameters into the formula. The desired yaw rate of the vehicle can then be calculated.

[0148] Step S207: Obtain the actual yaw rate of the vehicle.

[0149] Obtaining a vehicle's actual yaw rate typically relies on onboard sensors that measure the vehicle's motion in real time. Here are some methods for obtaining a vehicle's actual yaw rate:

[0150] 1. Measurement using sensors

[0151] Using a Yaw-G sensor, or IMU (Inertial Measurement Unit) sensor, the Yaw-G sensor (also known as a yaw rate sensor or yaw rate sensor) is specifically designed to measure the yaw rate of a vehicle. It is typically mounted near the vehicle's center of gravity and detects the vehicle's yaw rate using inertial measurement principles. Yaw-G sensors provide real-time and accurate yaw rate information and are an important component of vehicle stability control systems and advanced driver assistance systems. An IMU sensor is a device that integrates components such as an accelerometer and gyroscope to measure an object's three-axis attitude angles (yaw, pitch, and roll) as well as linear acceleration and angular velocity. In vehicles, IMU sensors are typically mounted near the vehicle's center of gravity to provide accurate information about the vehicle's motion status.

[0152] 2. Estimation based on vehicle dynamics model

[0153] Even without a Yaw-G sensor, a vehicle's yaw rate can be estimated using a vehicle dynamics model. This method requires utilizing parameters such as the vehicle's speed, acceleration, and steering angle, combined with the vehicle's physical characteristics and kinematic equations for calculation. However, this method is relatively complex, and the accuracy of the estimation results depends on the precision of the model and the parameters.

[0154] Step S208: Perform PID control based on the desired yaw rate and the actual yaw rate to obtain the rear wheel steering angle.

[0155] In vehicle control systems, the deviation between the actual yaw rate measured by IMU sensors and the desired yaw rate obtained based on vehicle dynamics or driver intent can be used to calculate the rear wheel steering angle via a PID (Proportional-Integral-Derivative) controller, thus achieving precise control of the vehicle's yaw motion. A brief step-by-step explanation follows:

[0156] Step S209: Generate a steering angle command for the final steering angle of the rear wheels based on the required rear wheel steering angle and the rear wheel steering angle, and send the steering angle command to the rear wheel steering actuator.

[0157] In vehicle rear-wheel steering control systems, a common control strategy is to combine the feedforward demand angle (rear wheel demand angle) and the feedback demand angle (rear wheel steering angle) to determine the final angle and the corresponding steering command. This strategy combines the predictive power of feedforward control with the corrective capability of feedback control to achieve more accurate and stable vehicle handling. Specifically, in this scheme, after calculating the rear wheel demand angle and the rear wheel steering angle, the two angles are weighted and summed (or according to other suitable combination strategies). The weighting coefficients can be adjusted according to control requirements, vehicle status, and external conditions to achieve the best control effect.

[0158] As can be seen from the above scheme, when the vehicle is determined to be on a split-road surface, the adhesion coefficient of the low-adhesion side and the actual acceleration of the vehicle are calculated. Then, based on the adhesion coefficient and the actual acceleration, the yaw moment of the vehicle is calculated. Further, based on the yaw moment and the rear wheel lateral stiffness, the required rear wheel steering angle is calculated to obtain the vehicle's desired yaw rate and actual yaw rate. Then, PID control is performed based on the desired yaw rate and the actual yaw rate to obtain the rear wheel steering angle. Based on the required rear wheel steering angle and the rear wheel steering angle, a steering angle command for the final rear wheel steering angle is generated and sent to the rear wheel steering actuator. This ensures that the vehicle can maintain straight-line travel on a split-road surface. Therefore, this scheme can reduce driver steering wheel intervention while maintaining straight-line travel on a split-road surface through split-road surface recognition, theoretical feedforward calculation, and closed-loop feedback control.

[0159] This embodiment discloses a specific scheme for determining whether a vehicle is located on a split-surface road. Specifically, the scheme includes: obtaining the slip ratios of the wheels on both sides of the vehicle; when the slip ratio of at least one wheel on either side is higher than a preset slip ratio threshold, and the slip ratios of the wheels on the other side are all lower than the preset slip ratio threshold, and the lateral acceleration of the vehicle is less than a certain threshold, the vehicle is determined to be on a split-surface road; otherwise, the vehicle is determined not to be on a split-surface road. For example, when the slip ratio of either of the two wheels on the left is higher than the preset slip ratio threshold, the slip ratios of both wheels on the right are lower than the preset slip ratio threshold, and the lateral acceleration of the vehicle is less than a certain threshold, then the base condition for a split-surface road with lower slip ratio on the left and higher slip ratio on the right is met. When the slip ratio of either of the two wheels on the right is higher than the preset slip ratio threshold, the slip ratios of both wheels on the left are lower than the preset slip ratio threshold, and the lateral acceleration of the vehicle is less than a certain threshold, then the base condition for a split-surface road with lower slip ratio on the right and higher slip ratio on the left is met.

[0160] In the technical solution disclosed in this embodiment, after determining that the vehicle is on a split road surface and before calculating the adhesion coefficient of the low-adhesion side, the method further includes: determining whether the user intends to keep the vehicle moving straight; when the user intends to keep the vehicle moving straight, activating the active control of the rear wheel steering and continuing to execute the steps: calculating the adhesion coefficient of the low-adhesion side and subsequent steps.

[0161] When determining whether a user intends to keep the vehicle traveling straight, the vehicle's driving and braking conditions can be considered. Specifically, when the vehicle is in driving mode, it is determined whether the user turns the steering wheel towards the side of the road with higher traction, and whether the turning angle is greater than a first preset angle. If the user turns the steering wheel towards the side of the road with higher traction, and the turning angle is greater than the first preset angle, it is determined that the user intends to keep the vehicle traveling straight. When the vehicle is in braking mode, it is determined whether the user turns the steering wheel towards the side of the road with lower traction, and whether the turning angle is greater than a second preset angle. If the user turns the steering wheel towards the side of the road with lower traction, and the turning angle is greater than the second preset angle, it is determined that the user intends to keep the vehicle traveling straight.

[0162] Specifically, regarding the determination of a left-low, right-high split road surface, if the vehicle is in driving mode, and the user turns the steering wheel to the right beyond a first preset angle, or if the vehicle is in braking mode and the user turns the steering wheel to the left beyond a first preset angle, it is assumed that the user intends to keep the vehicle moving straight. When either left wheel of the vehicle is in a low-friction state and either right wheel is in a high-friction state, and the user intends to keep the vehicle moving straight, if the vehicle's ABS or TCS is detected to be activated, the left-low, right-high split road surface indicator is maintained. When neither of the above conditions is met, the left-low, right-high split road surface indicator is deactivated. The left-low, right-high split road surface indicator is used to indicate that the vehicle is located on a left-low, right-high split road surface, and the user can determine that the vehicle is on a split road surface by using this indicator.

[0163] Regarding the determination of a right-low, left-high split road surface, if the vehicle is in driving mode, and the user turns the steering wheel to the left beyond a first preset angle, or if the vehicle is in braking mode and the user turns the steering wheel to the right beyond a first preset angle, it is assumed that the user intends to keep the vehicle moving straight. When either the right wheel of the vehicle is in a low-friction state and either the left wheel is in a high-friction state, and the user intends to keep the vehicle moving straight, if the vehicle's ABS or TCS is activated, the right-low, left-high split road surface indicator is maintained. When neither of the above conditions is met, the right-low, left-high split road surface indicator is deactivated. The right-low, left-high split road surface indicator is used to indicate that the vehicle is located on a right-low, left-high split road surface, and the user can determine that the vehicle is on a split road surface by using this indicator.

[0164] In the technical solution disclosed in the above embodiments of this application, when it is determined that the vehicle is on a split road surface, during the process of calculating the turning command, it is necessary to continuously determine whether the vehicle is on a split road surface or whether the vehicle's ABS function or TCS function is activated. If the vehicle is on a split road surface or the ABS function or TCS function is activated, it is necessary to continue calculating the adhesion coefficient of the low adhesion side in the next calculation cycle until the turning command is calculated and the turning command is sent to the rear wheel steering actuator. Then it is necessary to determine whether the vehicle is on a split road surface or whether the vehicle's ABS function or TCS function is activated until the vehicle is not on a split road surface or the vehicle's ABS function and TCS function are not activated. Only then can the calculation of the adhesion coefficient of the low adhesion side and subsequent steps be stopped.

[0165] This embodiment provides a vehicle control device for split-road surfaces. For details on the operation of each unit in the device, please refer to the above method embodiment.

[0166] The vehicle control device for split-road surfaces provided in the embodiments of the present invention will be described below. The vehicle control device for split-road surfaces described below can be referred to in correspondence with the vehicle control method for split-road surfaces described above.

[0167] See Figure 3 The vehicle control device for split-road surfaces disclosed in this application may include:

[0168] The first judgment unit 10 is used to determine whether the vehicle is located on the opposite road surface;

[0169] The adhesion coefficient calculation unit 20 is used to calculate the adhesion coefficient of the low adhesion side when the vehicle is on a split road surface.

[0170] Vehicle speed acquisition unit 30 is used to acquire the actual acceleration of the vehicle;

[0171] Yaw moment calculation unit 40 is used to calculate the yaw moment of the vehicle based on the adhesion coefficient and the actual acceleration;

[0172] The demand steering angle calculation unit 50 is used to calculate the demand steering angle of the rear wheel based on the yaw moment and the rear wheel lateral stiffness.

[0173] The PID control unit 60 is used to obtain the desired yaw rate of the vehicle, obtain the actual yaw rate of the vehicle, perform PID control based on the desired yaw rate and the actual yaw rate, and calculate the rear wheel steering angle.

[0174] The instruction sending unit 70 is used to generate a steering angle instruction for the final steering angle of the rear wheels based on the required rear wheel steering angle and the rear wheel steering angle, and send the steering angle instruction to the rear wheel steering actuator.

[0175] This application also provides an electronic device in its embodiments. (See reference...) Figure 4 The diagram illustrates a structural schematic suitable for implementing the electronic device in the embodiments of this application. The electronic device in the embodiments of this application may include, but is not limited to, fixed terminals such as mobile phones, laptops, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Figure 4 The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0176] like Figure 4 As shown, the electronic device may include a processing unit (e.g., a central processing unit, a graphics processing unit, etc.) 601, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage device 608 into a random access memory (RAM) 603. When the electronic device is powered on, the RAM 603 also stores various programs and data required for the operation of the electronic device. The processing unit 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0177] Typically, the following devices can be connected to I / O interface 605: input devices 606 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 607 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 608 including, for example, memory cards, hard drives, etc.; and communication devices 609. Communication device 609 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 4 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown. More or fewer devices may be implemented or have alternatively.

[0178] The electronic devices mentioned in this article can be ECU (Electronic Control Unit), VCU (Vehicle Control Unit), MCU (Micro Controller Unit), HCU (Hybrid Control Unit), etc.

[0179] This application also provides a computer program product including computer-readable instructions, which, when executed on an electronic device, cause the electronic device to implement any of the vehicle control methods for split-road surfaces provided in this application.

[0180] This application also provides a computer-readable storage medium carrying one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the vehicle control methods for split-road surfaces provided in this application.

[0181] All data and information collected and processed in this application are information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of such data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0182] For ease of description, the above system is described by dividing it into various modules based on their functions. Of course, in implementing this invention, the functions of each module can be implemented in one or more software and / or hardware components.

[0183] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0184] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0185] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0186] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0187] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A vehicle control method for split-road surfaces, characterized in that, include: Determine if the vehicle is on the opposite side of the road; When the vehicle is on a split road surface, calculate the adhesion coefficient on the side with lower adhesion. Obtain the vehicle's actual acceleration; The yaw moment of the vehicle is calculated based on the adhesion coefficient and the actual acceleration. The required rear wheel steering angle is calculated based on the yaw moment and rear wheel lateral stiffness. Obtain the vehicle's desired yaw rate; Obtain the vehicle's actual yaw rate; PID control is performed based on the desired yaw rate and the actual yaw rate to obtain the rear wheel steering angle; Based on the required rear wheel steering angle and the rear wheel steering angle, a steering angle command is generated for the final steering angle of the rear wheels, and the steering angle command is sent to the rear wheel steering actuator.

2. The vehicle control method for split-road surfaces according to claim 1, characterized in that, Determining whether a vehicle is on the opposite side of the road includes: The slip ratios of the wheels on both sides of the vehicle are obtained. When the slip ratio of at least one wheel on either side is higher than a preset slip ratio threshold, and the slip ratios of the wheels on the other side are all lower than the preset slip ratio threshold, the vehicle is determined to be on a split road surface. Otherwise, the vehicle is determined not to be on a split road surface.

3. The vehicle control method for split-road surfaces according to claim 2, characterized in that, After determining that the vehicle is on a split road surface, and before calculating the adhesion coefficient of the lower adhesion side, the following steps are also included: Determine if the user intends to keep the vehicle moving straight. If the user intends to keep the vehicle moving straight, activate the active control of the rear wheel steering and continue with the following steps: calculate the adhesion coefficient of the low-adhesion side and follow up with the next steps.

4. The vehicle control method for split-road surfaces according to claim 3, characterized in that, Determining whether a user intends to keep the vehicle moving straight includes: When the vehicle is in driving mode, it is determined whether the user turns the steering wheel toward the side with higher traction on the opposite side of the road, and whether the turning angle is greater than a first preset angle; if the user turns the steering wheel toward the side with higher traction on the opposite side of the road, and the turning angle is greater than the first preset angle, it is determined that the user has the intention to keep the vehicle moving straight. When the vehicle is braking, it is determined whether the user turns the steering wheel toward the side of the opposite road with low traction and whether the turning angle is greater than the second preset angle; if the user turns the steering wheel toward the side of the opposite road with low traction and the turning angle is greater than the second preset angle, it is determined that the user has the intention to keep the vehicle moving straight.

5. The vehicle control method for split-road surfaces according to claim 1, characterized in that, The process of obtaining the vehicle's desired yaw rate includes: Based on the steering wheel angle and vehicle speed, the desired yaw rate of the vehicle is calculated using a two-degree-of-freedom vehicle model.

6. The vehicle control method for split-road surfaces according to claim 1, characterized in that, Also includes: Determine whether the vehicle's ABS or TCS function is activated. If the ABS or TCS function is activated, execute the steps to calculate the adhesion coefficient of the low-adhesion side and subsequent steps until the steering angle command is sent to the rear wheel steering actuator.

7. A vehicle control device for split-road surfaces, characterized in that, include: The first judgment unit is used to determine whether the vehicle is located on the opposite road surface; The adhesion coefficient calculation unit is used to calculate the adhesion coefficient of the low-adhesion side when the vehicle is on a split road surface. The vehicle speed acquisition unit is used to obtain the actual acceleration of the vehicle; A yaw moment calculation unit is used to calculate the yaw moment of the vehicle based on the adhesion coefficient and the actual acceleration. The required steering angle calculation unit is used to calculate the required steering angle of the rear wheel based on the yaw moment and the rear wheel lateral stiffness. The PID control unit is used to obtain the desired yaw rate of the vehicle, obtain the actual yaw rate of the vehicle, perform PID control based on the desired yaw rate and the actual yaw rate, and calculate the rear wheel steering angle. The instruction sending unit is used to generate a steering angle instruction for the final steering angle of the rear wheels based on the required rear wheel steering angle and the rear wheel steering angle, and send the steering angle instruction to the rear wheel steering actuator.

8. A computer program product, characterized in that, It includes computer-readable instructions that, when executed on an electronic device, cause the electronic device to implement the vehicle control method for split-road surfaces as described in any one of claims 1 to 6.

9. An electronic device, characterized in that, It includes at least one processing device and a storage device connected to the processing device, wherein: The storage device is used to store computer programs; The processing device is used to execute the computer program to enable the electronic device to implement the vehicle control method for split-road surfaces as described in any one of claims 1 to 6.

10. A computer storage medium, characterized in that, The storage medium carries one or more computer programs that, when executed by an electronic device, enable the electronic device to implement the vehicle control method for split-road surfaces as described in any one of claims 1 to 6.

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