Steering control method, vehicle and storage medium

Abstract

The invention provides a steering control method, a vehicle and a storage medium, the vehicle performs independent control on each wheel based on an electronic mechanical braking system, and the method comprises the following steps: acquiring a steering angle signal of a steering wheel and an actual yaw angle of the vehicle; the target yaw angle of the vehicle is calculated according to the steering angle signal, and the steering state of the vehicle is determined according to the actual yaw angle and the target yaw angle; and based on the steering state, target braking force corresponding to each wheel of the vehicle is calculated, and an electronic mechanical braking system is driven to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action. According to the method, a power system and a braking system of the vehicle can be combined, the problems that due to the fact that the wheelbase is long, the vehicle is difficult to turn, the minimum turning radius is large, the vehicle cannot achieve expected steering and the like are solved, four-wheel independent control is used for assisting the vehicle in turning, and the turning flexibility of the vehicle is greatly improved.

Description

Technical Field

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

[0002] At present, the vehicle steering system can be divided into mechanical steering system and power steering system. Among them, the mechanical steering system uses the driver's physical strength as the steering energy, which is more laborious to operate and has poor steering sensitivity; the power steering system uses external force to help the driver complete the steering action to reduce the driver's steering control force.

[0003] In the related art, the vehicle is dynamically controlled by monitoring the yaw angle and adjusting the wheel braking force within a limited range to improve the turning performance of the vehicle.

[0004] However, during the vehicle's turning process, its minimum turning radius is affected by factors such as the steering system, braking system, and chassis layout. At present, the vehicle's braking system cannot achieve independent control of the four wheels, which makes the vehicle prone to turning difficulties and poor flexibility. During the turning process, the braking system is not combined with the power system, that is, there is no function for the braking system to send a request signal to the power system, and there is a lack of a strategy to request a change in the drive shaft torque. This may make it impossible for the vehicle to achieve the expected turning due to its long wheelbase and large minimum turning radius, which needs to be solved urgently. Summary of the invention

[0005] The present application provides a steering control method, a vehicle and a storage medium. The method can combine the power system and the braking system of the vehicle, solve the problems of difficulty in turning the vehicle due to a long wheelbase, and the inability of the vehicle to achieve the expected turning due to a large minimum turning radius. The method uses four-wheel independent control to assist the vehicle in turning, greatly improving the turning flexibility of the vehicle.

[0006] In a first aspect, a steering control method is provided, wherein the vehicle independently controls each wheel based on an electronic mechanical braking system, wherein the method comprises:

[0007] Acquire a steering wheel angle signal and an actual yaw angle of the vehicle; calculate a target yaw angle of the vehicle according to the steering wheel angle signal, and determine a steering state of the vehicle according to the actual yaw angle and the target yaw angle; calculate a target braking force corresponding to each wheel of the vehicle based on the steering state, and drive the electronic mechanical braking system to apply a corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0008] Through the above technical solution, the present application determines the stability of the current vehicle based on the actual yaw angle obtained and the expected yaw angle output, and then accurately determines whether the current steering state of the vehicle is understeering or oversteering, and calculates the target braking force required for the four wheels based on different steering states, so that the vehicle completes the expected steering action. Therefore, the present application can realize the combination of the vehicle's power system and braking system, use the four-wheel independent control to assist the vehicle in turning, effectively reduce the maximum turning radius, and greatly improve the flexibility of vehicle turning.

[0009] In combination with the first aspect, in certain possible implementations, when driving the electronic mechanical braking system to apply the corresponding target braking force to each wheel, it also includes: calculating the difference between the actual yaw angle and the target yaw angle; based on the difference, determining the target torque of the drive motor from a preset drive motor torque calibration table; if the current vehicle speed is greater than the preset vehicle speed, reducing the current torque of the drive motor to the target torque according to a preset torque reduction strategy; otherwise, increasing the current torque of the drive motor to the target torque according to a preset torque increase strategy.

[0010] Through the above technical solution, the present application calibrates the target torque of the drive motor by the difference between the actual yaw angle and the target yaw angle, and corrects the target torque of the drive motor in combination with the vehicle speed. Therefore, the present application can reduce the drive motor torque when the vehicle speed is too fast, and increase the drive motor torque when the vehicle speed is too slow, thereby assisting the vehicle in turning and effectively improving the vehicle's turning passability.

[0011] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, calculating the target braking force corresponding to each wheel of the vehicle based on the steering state includes: obtaining the current brake pedal opening, the current brake disc temperature and the current vehicle speed of the vehicle; based on the steering state, calculating the target braking force corresponding to each wheel according to the current vehicle speed, the current brake pedal opening, the current brake disc temperature, the current vehicle state and the current target yaw angle.

[0012] Through the above technical solution, the present application can accurately calculate the target braking force corresponding to each wheel through the brake pedal opening, the current brake disc temperature and the current wheel speed, so as to achieve precise control of each wheel, thereby improving the steering performance and sensitivity of the vehicle, helping the driver to complete the steering action and reducing the driver's steering control force.

[0013] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, determining the steering state of the vehicle based on the actual yaw angle and the target yaw angle includes: calculating a first difference between the target yaw angle and the actual yaw angle, and determining whether the first difference is greater than a first threshold value; if the first difference is greater than the first threshold value, determining that the steering state is an understeering state.

[0014] Through the above technical solution, the present application calculates the difference between the expected output yaw angle and the actual yaw angle, and when the value is greater than the threshold calculated by the vehicle body sensor signal, the present application determines that the vehicle is in understeering state. Therefore, the present application can judge the current steering state of the vehicle based on the vehicle body parameters and different operating conditions of the vehicle, thereby achieving more accurate vehicle steering control and improving the vehicle's turning pass rate.

[0015] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, determining the steering state of the current vehicle based on the actual yaw angle and the target yaw angle also includes: calculating a second difference between the actual yaw angle and the target yaw angle, and determining whether the second difference is greater than a second threshold value; if the second difference is greater than the second threshold value, determining that the steering state is an oversteering state.

[0016] Through the above technical solution, the present application calculates the difference between the actual yaw angle and the target yaw angle, and when the difference between the two is too large, determines that the steering state of the vehicle at this time is an oversteering state. Therefore, the present application can determine whether the vehicle is in an oversteering state by the deviation between the actual size of the yaw angle and the expected output yaw angle, thereby achieving more accurate vehicle steering control and improving the vehicle turning pass rate.

[0017] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, after calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, it also includes: obtaining the steering intention of the vehicle; based on the steering state and the steering intention, judging whether the target braking force corresponding to each wheel meets the preset braking condition; if the target braking force corresponding to each wheel meets the preset braking condition, allowing the electronic mechanical braking system to be driven to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0018] Through the above technical solution, before controlling the braking of each wheel through the electronic mechanical braking system, the present application needs to obtain the vehicle's steering intention and determine whether the calculated target braking force can drive the caliper motor to complete the corresponding steering action. Therefore, the steering control strategy of the present application can ensure the safety and smoothness of the vehicle's steering, so that the current steering action meets the driver's wishes and driving mode requirements, greatly improving the intelligence and comfort of driving.

[0019] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, obtaining the turning intention of the vehicle includes: obtaining the current turn signal on state of the vehicle; and determining the turning intention of the vehicle based on the current turn signal on state.

[0020] Through the above technical solution, since the corresponding turn signal line will light up after the turn signal is turned on, the present application can determine which turn signal is on, and then determine the vehicle's steering intention, so as to achieve precise control of the vehicle's steering.

[0021] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, judging whether the target braking force corresponding to each wheel meets the preset braking condition based on the steering state and the steering intention includes: determining the outer wheel and the inner wheel of the vehicle according to the steering intention; if the steering state is an understeering state, then when the target braking force of the outer wheel of the vehicle is greater than the target braking force of the inner wheel of the vehicle, judging that the target braking force corresponding to each wheel meets the preset braking condition; if the steering state is an oversteering state, then when the target braking force of the outer wheel of the vehicle is less than the target braking force of the inner wheel of the vehicle, judging that the target braking force corresponding to each wheel meets the preset braking condition.

[0022] Through the above technical solution, the present application distinguishes the outer wheels and the inner wheels of the vehicle according to the steering intention, and according to the current steering state of the vehicle, through the magnitude of the inner / outer wheel braking force, respectively determines whether the target braking force corresponding to each wheel meets the preset braking condition. Therefore, the present application can avoid the problem of vehicle misadjustment by judging whether the target braking force meets the preset braking condition, improve the accuracy of vehicle steering control, and enable the vehicle to complete the steering action.

[0023] In a second aspect, a steering control device for a vehicle is provided, wherein the vehicle independently controls each wheel based on an electronic mechanical braking system, wherein the device comprises:

[0024] An acquisition module is used to acquire a steering wheel angle signal and an actual yaw angle of the current vehicle;

[0025] a determination module, configured to calculate a target yaw angle of the vehicle according to the turning angle signal, and determine a steering state of the current vehicle according to the actual yaw angle and the target yaw angle;

[0026] The control module is used to calculate the target braking force corresponding to each wheel of the vehicle based on the steering state, and drive the electronic mechanical braking system to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0027] In conjunction with the second aspect, in some possible implementations, when driving the electronic mechanical braking system to apply the corresponding target braking force to each wheel, the control module is further configured to:

[0028] Calculate the difference between the actual yaw angle and the target yaw angle; determine the target torque of the drive motor from a preset drive motor torque calibration table based on the difference; when the current vehicle speed is greater than the preset vehicle speed, reduce the current torque of the drive motor to the target torque according to a preset torque reduction strategy; otherwise, increase the current torque of the drive motor to the target torque according to a preset torque increase strategy.

[0029] In combination with the second aspect and the above implementation, in some possible implementations, the control module is further used to:

[0030] Obtain the current brake pedal opening, current brake disc temperature and current wheel speed of the vehicle; based on the steering state, calculate the target braking force corresponding to each wheel according to the current wheel speed, the current brake pedal opening, the current brake disc temperature, the current vehicle state and the current target yaw angle.

[0031] In combination with the second aspect and the foregoing implementation manner, in some possible implementation manners, the determining module is specifically configured to:

[0032] A first difference between the target yaw angle and the actual yaw angle is calculated, and it is determined whether the first difference is greater than a first threshold value; when the first difference is greater than the first threshold value, it is determined that the steering state is an understeering state.

[0033] In combination with the second aspect and the foregoing implementation manner, in some possible implementation manners, the determining module is further used to:

[0034] A second difference between the actual yaw angle and the target yaw angle is calculated, and it is determined whether the second difference is greater than a second threshold value; if the second difference is greater than the second threshold value, it is determined that the steering state is an oversteering state.

[0035] In combination with the second aspect and the above implementation, in some possible implementations, after calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, the control module is further used to:

[0036] Acquire the steering intention of the vehicle; based on the steering state and the steering intention, determine whether the target braking force corresponding to each wheel meets the preset braking condition; when the target braking force corresponding to each wheel meets the preset braking condition, allow the electronic mechanical braking system to be driven to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0037] In combination with the second aspect and the above-mentioned implementation methods, in some possible implementation methods, after calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, the control module is also used to: obtain the current turn signal on state of the vehicle; and determine the steering intention of the vehicle based on the current turn signal on state.

[0038] In combination with the second aspect and the above implementation, in some possible implementations, the determining, based on the steering state and the steering intention, whether the target braking force corresponding to each wheel satisfies a preset braking condition, the control module is specifically configured to:

[0039] The outer wheels and the inner wheels of the vehicle are determined according to the steering intention; if the steering state is an understeering state, then when the target braking force of the outer wheels of the vehicle is greater than the target braking force of the inner wheels of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking condition; if the steering state is an oversteering state, then when the target braking force of the outer wheels of the vehicle is less than the target braking force of the inner wheels of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking condition.

[0040] In a third aspect, a vehicle is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method in the first aspect or any possible implementation of the first aspect.

[0041] In a fourth aspect, a computer-readable storage medium is provided, which stores a computer program code. When the computer program code runs on a computer, the computer executes the method in the above-mentioned first aspect or any possible implementation manner of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic diagram of a vehicle structure of a specific embodiment of the present application;

[0043] Figure 2 is a flow chart of a steering control method provided by an embodiment of the present application;

[0044] Figure 3 is a schematic diagram of target yaw calculation according to a specific embodiment of the present application;

[0045] Figure 4 is a schematic diagram of a control interface of a specific embodiment of the present application;

[0046] Figure 5 is a schematic diagram of the steering control logic of a specific embodiment of the present application;

[0047] Figure 6 is a flow chart of a steering control method according to a specific embodiment of the present application;

[0048] Figure 7 is a block diagram of a steering control device provided in an embodiment of the present application;

[0049] Figure 8 It is a block diagram of a vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0050] The technical solution in the present application will be described clearly and in detail below in conjunction with the accompanying drawings. In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0051] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as suggesting or implying 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 the features.

[0052] Traditional vehicle steering systems can be divided into mechanical steering systems and power steering systems. They do not combine the power system with the braking system to complete the vehicle's steering. Therefore, during the vehicle's steering process, the vehicle may not be able to achieve the expected steering due to the long wheelbase and large minimum turning radius. In addition, the braking system in the relevant technology cannot achieve four-wheel independent control, resulting in low sensitivity in vehicle steering, which may cause accidents such as vehicle skidding and collision.

[0053] In order to solve the above problems, the present application proposes a steering control method based on an electromechanical brake system, which can realize independent control of each wheel. It can be understood by those skilled in the art that the electromechanical brake system (EMB) is a braking system in a completely new sense, which completely abandons the traditional hydraulic pipeline, uses small and light wire lines as the transmission medium of signals and energy, uses clean and environmentally friendly electricity to provide energy source for the entire braking system, uses fast-response and high-efficiency electric motors to drive the terminal brake actuator to brake, and uses high-precision and intelligent sensors to detect the driver's braking intention. It is a truly wire-controlled brake system without mechanical backup.

[0054] Therefore, the present application can combine the electronic mechanical braking system with the power system, and realize that the controllers of the four wheels independently control the respective braking forces. Thus, the present application can effectively reduce the minimum turning radius and improve the flexibility and operability of the vehicle turning.

[0055] Next, the vehicle structure involved in the steering control method of the embodiment of the present application is described. Figure 1 , Figure 1 A schematic diagram of a vehicle structure according to a specific embodiment of the present application.

[0056] Specifically, Figure 1 As shown, the present application sets wheel-end MCUs (Microcontroller Unit) at the four wheels of the vehicle, and the four wheel-end MCUs are MCU_FR, MCU_FL, MCU_RR and MCU_RL, respectively, to achieve independent braking of the four wheels, wherein MCU_FR is the right front wheel end, MCU_FL is the left front wheel end, MCU_RR is the right rear wheel end, and MCU_RL is the left rear wheel end. In addition, the present application does not specifically limit the setting method of the wheel-end MCU, and those skilled in the art can set it according to actual conditions.

[0057] An electronic mechanical braking system is provided in the vehicle of the embodiment of the present application. The domain controller in the system is externally connected to two power supplies (power supply 1 and power supply 2). Power supply 1 and power supply 2 supply power to the domain controller and four wheel-end MCUs. The domain controller can obtain data such as the vehicle's speed, acceleration, steering angle, etc. through sensors, and judge the vehicle status based on these data to control the operation of the brakes.

[0058] The steering control method of an embodiment of the present application is described below with reference to the accompanying drawings. The vehicle of the embodiment of the present application independently controls each wheel based on an electronic mechanical braking system.

[0059] Figure 2It is a schematic flow chart of the steering control method provided in an embodiment of the present application.

[0060] For example, Figure 2 As shown, the steering control method includes the following steps:

[0061] In step S201 , a steering wheel angle signal and an actual yaw angle of the vehicle are acquired.

[0062] Among them, the steering wheel angle signal of the embodiment of the present application may include information such as the steering wheel rotation angle, rotation direction and steering speed, which is the basis for the embodiment of the present application to judge the size of the lateral force when the vehicle is turning. The angle signal can be obtained by the steering wheel angle sensor and transmitted to the domain controller of the electronic mechanical braking system through the bus.

[0063] Specifically, the actual yaw angle of the embodiment of the present application refers to the angle between the front of the vehicle and the ground coordinate system X when the vehicle is currently driving. Taking into account that the actual yaw angle of the vehicle can reflect the severity of the vehicle's turn, the present application judges the steering stability of the vehicle based on the deviation between the actual yaw angle and the target yaw angle.

[0064] Therefore, the electronic mechanical braking system domain controller of the embodiment of the present application can receive the steering wheel angle signal and the actual yaw angle of the vehicle, and identify the driver's intention to achieve precise control of the vehicle steering.

[0065] In step S202, a target yaw angle of the vehicle is calculated according to the turning angle signal, and a steering state of the vehicle is determined according to the actual yaw angle and the target yaw angle.

[0066] Among them, the steering state of the vehicle includes understeering state and oversteering state. This application needs to accurately judge the steering state of the vehicle and control the vehicle according to the current steering state to achieve efficient turning action and prevent the vehicle from skidding, rollover and other accidents.

[0067] Specifically, Figure 3 Schematic diagram of target yaw calculation of an embodiment of the present application. The target yaw angle of the present application can be calculated based on a single track model, such as Figure 3 As shown, the embodiment of the present application obtains the desired yaw based on the Ackermann equation according to the steering wheel angle, combines the vehicle speed, increases the yaw angle limit according to the current motion state of the vehicle, and corrects the target yaw according to the driver's operating state. After filtering, in order to increase the robustness of the system, the calculated value is compensated accordingly, and finally the target yaw angle expected by the driver is output.

[0068] Furthermore, in some embodiments, the steering state of the vehicle is determined based on the actual yaw angle and the target yaw angle, including: calculating a first difference between the target yaw angle and the actual yaw angle, and determining whether the first difference is greater than a first threshold value; if the first difference is greater than the first threshold value, determining that the steering state is an understeering state.

[0069] Furthermore, in some embodiments, determining the steering state of the current vehicle based on the actual yaw angle and the target yaw angle also includes: calculating a second difference between the actual yaw angle and the target yaw angle, and determining whether the second difference is greater than a second threshold value; if the second difference is greater than the second threshold value, determining that the steering state is an oversteering state.

[0070] Specifically, the present application makes a difference between the target yaw angle and the actual yaw angle, and sets a first threshold value. When the difference between the target yaw angle and the actual yaw angle exceeds the first threshold value, that is, the expected output yaw angle is greater than the actually detected yaw angle, the steering state at this time is determined to be an understeering state. The present application makes a difference between the actual yaw angle and the target yaw angle, and sets a second threshold value. When the difference between the actual yaw angle and the target yaw angle exceeds the second threshold value, that is, the actually detected yaw angle is greater than the expected output yaw angle, the steering state at this time is determined to be an oversteering state.

[0071] Therefore, the present application determines the severity of the vehicle's steering, that is, the vehicle's steering state, by calculating the deviation between the target yaw angle and the actual yaw angle. The basis for determination is by comparing with the calibrated threshold value. The following examples will specifically introduce the method for obtaining the first threshold value and the second threshold value of the embodiments of the present application.

[0072] It is understandable that when a vehicle is turning, the vehicle will move in a curve. At this time, the vehicle will be affected by lateral acceleration, which has an important impact on the stability of the vehicle's turning. Therefore, the present application obtains the lateral acceleration through an accelerometer installed on the wheel, and calculates the rate of change of the lateral acceleration, which is used to determine the first threshold value of the embodiment of the present application.

[0073] Optionally, in order to avoid the vehicle from slipping when turning, the present application also considers the road adhesion coefficient when calculating the first threshold value. In addition, the present application takes into account the different driving modes of the current vehicle, and its speed and braking force are different. Therefore, the first threshold value is calculated and corrected in combination with the current driving mode and working conditions.

[0074] Therefore, the present application can obtain the vehicle's lateral acceleration, lateral acceleration change rate, road adhesion coefficient, current driving mode and current working conditions before determining whether the first difference is greater than the first threshold value, and calculate the first threshold value of the embodiment of the present application based on the lateral acceleration, lateral acceleration change rate, road adhesion coefficient and steering angle signal to determine whether the vehicle state is understeering, thereby effectively improving the accuracy of determining the vehicle state.

[0075] Furthermore, when calculating the second threshold value, the present application mainly includes two parts: basic threshold limitation and threshold compensation. The basic threshold value of the embodiment of the present application can be calculated according to the vehicle state, that is, the current driving mode, which may include energy-saving mode, sports mode, etc. It can be understood that different driving modes correspond to different basic threshold values. For example, the sports mode pays more attention to power and handling, and the required basic threshold value is higher than that of the energy-saving mode; for example, the sports mode usually intervenes in oversteering earlier than the normal mode, so the basic threshold value of the normal mode is lower. Therefore, according to the current driving mode, the present application can obtain data such as the current speed change logic and driving style of the vehicle, so as to set different basic threshold values ​​according to the different driving modes selected by the driver.

[0076] Optionally, the application needs to correct the determined basic threshold value, dynamically judge the vehicle state and instantaneous working condition, so as to obtain a more accurate threshold value. The threshold compensation of the embodiment of the application is mainly aimed at different working conditions of the vehicle, and the basic threshold value is reasonably corrected according to different working conditions. The working conditions that need to be corrected include at least the following situations: ABS (Antilock Brake System, anti-lock braking system) braking condition, all-terrain condition, low-speed condition, etc.

[0077] In step S203, based on the steering state, the target braking force corresponding to each wheel of the vehicle is calculated, and the electronic mechanical braking system is driven to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0078] It can be understood that after determining the current steering state of the vehicle, the present application can calculate the braking force corresponding to each wheel according to the steering state, so that the actuator of the caliper motor corresponding to each wheel receives the target braking force signal issued by the domain controller in the electronic mechanical braking system, and applies the corresponding target braking force to each wheel according to the target braking force signal.

[0079] It should be noted that when the embodiment of the present application drives the electronic mechanical brake system to apply the corresponding target braking force to each wheel, the target braking force is applied to the corresponding wheel by controlling the caliper motor corresponding to each wheel respectively.

[0080] In some cases, in order to improve the vehicle's steering stability and assist the vehicle in turning smoothly, the present application also needs to calculate the target torque of the drive motor according to the vehicle's state to further improve the vehicle's turning sensitivity and maneuverability.

[0081] The following examples are listed to specifically introduce the calculation method of the target braking force of each wheel and the target torque of the drive motor, as well as the vehicle steering control strategy of the embodiments of the present application.

[0082] Optionally, in some embodiments, based on the steering state, the target braking force corresponding to each wheel of the vehicle is calculated, including: obtaining the vehicle's current brake pedal opening, current brake disc temperature and current vehicle speed; based on the steering state, calculating the target braking force corresponding to each wheel according to the current vehicle speed, current brake pedal opening, current brake disc temperature, current vehicle state and current target yaw angle.

[0083] Among them, the current brake pedal opening of the vehicle can be obtained by a pedal travel sensor external to the electronic mechanical brake system. Since the current brake pedal opening of the vehicle can reflect the force or opening applied by the driver on the brake pedal, the present application can calculate the target braking force corresponding to each wheel in combination with the data to improve driving safety and braking performance. The current vehicle speed of the embodiment of the present application can be obtained by a wheel speed sensor external to the electronic mechanical brake system. In addition, the present application takes into account that the temperature of the brake disc will increase when the vehicle is braking. In order to avoid affecting the turning performance due to the excessively high temperature of the brake disc, the brake disc temperature is combined when calculating the target braking force to effectively prevent the increase of braking resistance and further improve the sensitivity of turning.

[0084] It should be noted that Figure 4 This is a schematic diagram of a control interface of a specific embodiment of the present application, such as Figure 4 As shown, the above-mentioned data signals such as brake pedal opening, brake disc temperature and vehicle speed are respectively acquired by corresponding sensors, and the domain controller of the electronic mechanical braking system receives the corresponding data signals, obtains the target braking force through calculation, and then inputs the target braking force signal to the caliper motor corresponding to each wheel. The caliper motor applies the target braking force to each wheel to complete the steering action.

[0085] Furthermore, the present application can calculate the difference between the actual yaw angle and the target yaw angle. Since the yaw angle difference can reflect the braking force deviation of the left and right wheels, the present application can calculate the target braking force of the corresponding wheel based on the yaw angle difference, combined with data such as brake pedal opening, brake disc temperature and vehicle speed. Specifically, the present application can pre-calibrate the yaw angle difference and the target braking force, and obtain the target braking force of each wheel by looking up a table.

[0086] In some embodiments, when the brake disc temperature is less than a certain threshold (calibrated value), the target braking force required for each wheel is obtained based on the corresponding relationship between the actual yaw angle and the target yaw angle difference. When the domain controller of the electronic mechanical braking system recognizes the braking force corresponding to the brake pedal opening, it automatically compensates the target braking force and calculates the actual target braking force. At the same time, the actual target braking force is corrected through real-time feedback of the vehicle speed signal.

[0087] In other embodiments, when the brake disc temperature is greater than a certain threshold value (calibrated value), the target braking force is larger, and within the range of different brake disc temperatures, there is a unique corresponding relationship between the target braking force and the difference between the actual yaw angle and the target yaw angle. When the domain controller of the electronic mechanical braking system recognizes the braking force corresponding to the brake pedal opening, it automatically compensates the target braking force, calculates the actual target braking force, and corrects the actual target braking force through real-time feedback of the vehicle speed signal.

[0088] Therefore, the present application can accurately calculate the target braking force required for each wheel based on the brake disc temperature, the current target yaw angle, and the steering state, and correct the target braking force according to the brake pedal opening and vehicle speed signal to achieve precise control of each wheel.

[0089] Optionally, in some embodiments, when the driving electronic mechanical braking system applies the corresponding target braking force to each wheel, it also includes: calculating the difference between the actual yaw angle and the target yaw angle; based on the difference, determining the target torque of the drive motor from a preset drive motor torque calibration table; if the current vehicle speed is greater than the preset vehicle speed, reducing the current torque of the drive motor to the target torque according to a preset torque reduction strategy; otherwise, increasing the current torque of the drive motor to the target torque according to a preset torque increase strategy.

[0090] Specifically, the present application calibrates the target torque of the drive motor by the difference between the actual yaw angle and the target yaw angle, i.e., the yaw angle difference, and then corrects the actual drive motor torque in combination with the vehicle speed to obtain the optimal target torque value for controlling the drive motor and improve the steering performance of the vehicle.

[0091] Based on the above embodiments, it can be understood that the actual yaw angle of the embodiment of the present application can be measured by a yaw angle sensor installed on the vehicle, while the target yaw angle is calculated by the above-mentioned dynamic parameters, the state of the vehicle and the driver's input, so that the present application can obtain the difference between the actual yaw angle and the target yaw angle. Since there is a corresponding relationship between the target torque of the drive motor and the difference between the actual yaw angle and the target yaw angle, the present application can pre-calibrate the yaw angle difference and the target torque of the drive motor, and obtain the target torque of the drive motor by looking up a table.

[0092] Furthermore, the domain controller of the electronic mechanical brake system of the embodiment of the present application obtains the current speed of the vehicle, and when the current speed is greater than the preset speed (calibrated amount), the torque of the drive motor is automatically compensated, that is, the torque reduction strategy preset in the embodiment of the present application is adopted, that is, the torque of the drive motor is reduced to the target torque; when the current speed is less than the preset speed (calibrated amount), the torque increase strategy preset in the embodiment of the present application needs to be adopted, that is, the torque of the drive motor is increased to the target torque. Thus, the present application can correct the torque of the drive motor through real-time feedback of the vehicle speed signal while driving the electronic mechanical brake system to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, thereby assisting the vehicle steering according to the target torque of the drive motor, and further improving the accuracy of the vehicle steering control.

[0093] Optionally, in some embodiments, after calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, it also includes: obtaining the steering intention of the vehicle; based on the steering state and the steering intention, determining whether the target braking force corresponding to each wheel meets the preset braking conditions; if the target braking force corresponding to each wheel meets the preset braking conditions, allowing the driving electronic mechanical braking system to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0094] The vehicle's turning intention refers to the driver's need to turn or change the driving direction while driving.

[0095] Optionally, in some embodiments, obtaining the turning intention of the vehicle includes: obtaining the current turn signal on state of the vehicle; and determining the turning intention of the vehicle according to the current turn signal on state.

[0096] It can be understood that, since the corresponding turn signal line will light up after the turn signal is turned on, the present application can determine which turn signal is on, and then determine the vehicle's turning intention, so as to achieve precise control of the vehicle's steering.

[0097] Specifically, the present application obtains the accelerator pedal signal, steering wheel angle signal, etc. through the domain controller of the electronic mechanical braking system. After obtaining the steering intention of the vehicle, it is necessary to determine whether the target braking force corresponding to each wheel meets the preset braking conditions. After the preset braking conditions are met, each wheel is controlled. The present application can effectively avoid the problem of misadjustment. Furthermore, the present application can control the electronic mechanical braking system to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the current steering action meets the driver's wishes and the requirements of the driving mode, greatly improving the intelligence and comfort of driving.

[0098] Optionally, in some embodiments, based on the steering state and the steering intention, it is determined whether the target braking force corresponding to each wheel meets the preset braking conditions, including: determining the outer wheels and the inner wheels of the vehicle according to the steering intention; if the steering state is an understeering state, then when the target braking force of the outer wheels of the vehicle is greater than the target braking force of the inner wheels of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking conditions; if the steering state is an oversteering state, then when the target braking force of the outer wheels of the vehicle is less than the target braking force of the inner wheels of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking conditions.

[0099] It can be understood that when the vehicle is turning, the tire on the same side as the steering wheel turning direction is the vehicle's inner wheel, and the tire on the opposite side from the steering wheel turning direction is the vehicle's outer wheel. Therefore, the present application can distinguish between the vehicle's outer wheels and the vehicle's inner wheels based on the vehicle's steering intention, that is, the direction in which the driver controls the steering wheel to turn.

[0100] In some cases, the vehicle's steering state is an understeering state. If the target braking force of the vehicle's outer wheels is greater than the target braking force of the vehicle's inner wheels, it is determined that the target braking force corresponding to each wheel meets the preset braking conditions. At this time, a larger braking force is applied to the vehicle's inner wheels. Combined with the vehicle speed, the torque of the drive motor is reduced when the vehicle speed is too fast, and the torque of the drive motor is increased when the vehicle speed is too slow, to assist the vehicle in turning.

[0101] In other cases, the vehicle's steering state is an oversteer state. If the target braking force of the vehicle's outer wheels is less than the target braking force of the vehicle's inner wheels, it is determined that the target braking force corresponding to each wheel meets the preset braking conditions. At this time, the target braking force of the vehicle's outer wheels is controlled to be greater than that of the inner wheels. Combined with the vehicle speed, the drive motor torque is reduced when the vehicle speed is too fast, and the drive motor torque is increased when the vehicle speed is too slow, to assist the vehicle in turning.

[0102] Therefore, the present application controls the four-wheel braking force through the electronic mechanical brake system domain controller, and sends a target torque request to the drive motor to assist the vehicle in completing the steering action, thereby greatly improving the vehicle's steering flexibility.

[0103] In order to enable those skilled in the art to further understand the vehicle steering control logic introduced in the above embodiments, the following embodiments are listed in conjunction with the accompanying drawings to schematically illustrate the vehicle steering control system based on wire control braking provided by the present application.

[0104] Specifically, Figure 5 This is a schematic diagram of the steering control logic of a specific embodiment of the present application, such as Figure 5 As shown, the steering control system of the present application may include: a signal processing module, a target yaw angle calculation module, a dynamic control module, a target braking force calculation module and a target torque calculation module.

[0105] The signal processing module is used to receive wheel speed signals, brake pedal travel signals, steering wheel angle signals, etc., process these signals accordingly, and output them to the target yaw angle calculation module;

[0106] The target yaw angle calculation module is used to increase the limit value according to the current motion state of the vehicle based on the single track model, and to correct the target based on the driver's operating state. After filtering, it finally outputs the driver's expected target yaw angle;

[0107] The dynamic control module is used to judge the vehicle status and instantaneous working conditions, such as actual yaw angle, vehicle speed and other data;

[0108] The target braking force calculation module is used to calculate the target braking force corresponding to each wheel according to the wheel speed signal, the brake pedal travel signal, the brake disc temperature signal, the vehicle state signal and the target yaw angle signal;

[0109] The target torque calculation module is used to calculate the target torque of the drive motor according to the accelerator pedal signal, the drive motor speed signal, the drive motor torque signal, the vehicle speed signal, the target yaw angle signal, the actual yaw angle signal and the vehicle status signal.

[0110] Therefore, the present application obtains the body sensor signal, combines the vehicle state and instantaneous working conditions to calculate the target braking force of each wheel and the target torque of the drive motor, so as to achieve more efficient vehicle steering action.

[0111] It should be noted that the modules divided in the above embodiments are only used to illustrate the vehicle steering control logic of the present application. The present application does not make specific limitations on the division of modules in the embodiments. The vehicle steering control system based on wire control braking in the embodiments of the present application includes but is not limited to the above modules, and those skilled in the art can set them according to actual conditions.

[0112] Furthermore, in order to enable those skilled in the art to understand the steering control method of the present application, the following examples are listed in conjunction with the accompanying drawings to schematically illustrate the specific steps of the method.

[0113] Specifically, Figure 6 This is a flow chart of a steering control method according to a specific embodiment of the present application. Figure 6 As shown, the method comprises the following steps:

[0114] Step S601: The domain controller of the electronic mechanical brake system receives the steering signal, identifies the driver's steering intention, receives the steering wheel angle, the accelerator pedal opening, the drive motor speed, and the 、 Signals such as brake disc temperature;

[0115] Step S602, the domain controller of the electronic mechanical brake system identifies and determines whether the vehicle steering state is an oversteering state or an understeering state, receives a steering wheel angle signal, and calculates a caliper target braking force and a drive motor target torque in combination with an accelerator pedal signal, a drive motor torque signal, a drive motor speed signal, a wheel speed signal, a brake pedal signal, etc.;

[0116] Step S603, the caliper motor actuator and the drive motor controller receive the target braking force signal and the target torque signal respectively;

[0117] Step S604, applying different target braking forces to the caliper motor of each wheel; the driving motor controller receives the target torque to implement torque control;

[0118] Step S605: The vehicle completes the turning operation under the cooperation of the braking system and the driving system.

[0119] Therefore, the present application controls the wheel-end MCU of each wheel respectively through the domain controller of the electronic mechanical braking system to achieve independent braking of the four wheels, and assists the vehicle in turning through a control method based on independent wire-controlled braking-assisted steering on four wheels, thereby improving the vehicle's turning passability.

[0120] In summary, the steering control method of the present application obtains the steering wheel angle signal and the actual yaw angle of the vehicle, calculates the target yaw angle of the vehicle according to the steering angle signal, and determines the steering state of the vehicle according to the actual yaw angle and the target yaw angle. Based on the steering state, the target braking force corresponding to each wheel of the vehicle is calculated, and the electronic mechanical braking system is driven to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action. This method can combine the power system and the braking system of the vehicle, solve the problems of difficulty in turning due to the long wheelbase, the inability of the vehicle to achieve the expected steering due to the large minimum turning radius, etc., and use four-wheel independent control to assist the vehicle in turning, greatly improving the flexibility of vehicle turning.

[0121] Figure 7 It is a structural schematic diagram of a steering control device provided in an embodiment of the present application.

[0122] For example, Figure 7 As shown, the steering control device may include: an acquisition module 100 , a determination module 200 and a control module 300 .

[0123] Among them, the acquisition module 100 is used to obtain the steering wheel angle signal and the actual yaw angle of the vehicle; the determination module 200 is used to calculate the target yaw angle of the vehicle according to the steering angle signal, and determine the steering state of the vehicle according to the actual yaw angle and the target yaw angle; the control module 300 is used to calculate the target braking force corresponding to each wheel of the vehicle based on the steering state, and drive the electronic mechanical braking system to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0124] Optionally, in some embodiments, when the electronic mechanical braking system is driven to apply the corresponding target braking force to each wheel, the control module 300 is also used to: calculate the difference between the actual yaw angle and the target yaw angle; based on the difference, determine the target torque of the drive motor from a preset drive motor torque calibration table; when the current vehicle speed is greater than the preset vehicle speed, reduce the current torque of the drive motor to the target torque according to a preset torque reduction strategy; otherwise, increase the current torque of the drive motor to the target torque according to a preset torque increase strategy.

[0125] Optionally, in some embodiments, the control module 300 is also used to: obtain the vehicle's current brake pedal opening, current brake disc temperature and current vehicle speed; based on the steering state, calculate the target braking force corresponding to each wheel according to the current vehicle speed, current brake pedal opening, current brake disc temperature, current vehicle state and current target yaw angle.

[0126] Optionally, in some embodiments, the determination module 200 is specifically used to: calculate a first difference between the target yaw angle and the actual yaw angle, and determine whether the first difference is greater than a first threshold value; if the first difference is greater than the first threshold value, determine that the steering state is an understeering state.

[0127] Optionally, in some embodiments, the determination module 200 is further used to: calculate a second difference between the actual yaw angle and the target yaw angle, and determine whether the second difference is greater than a second threshold value; if the second difference is greater than the second threshold value, determine that the steering state is an oversteering state.

[0128] Optionally, in some embodiments, after calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, the control module 300 is further used to: obtain the steering intention of the vehicle; determine whether the target braking force corresponding to each wheel meets the preset braking conditions based on the steering state and the steering intention; and when the target braking force corresponding to each wheel meets the preset braking conditions, allow the driving electronic mechanical braking system to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

[0129] Optionally, in some embodiments, after calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, the control module 300 is further used to: obtain the current turn signal on state of the vehicle; and determine the steering intention of the vehicle according to the current turn signal on state.

[0130] Optionally, in some embodiments, based on the steering state and the steering intention, it is determined whether the target braking force corresponding to each wheel meets the preset braking conditions. The control module 300 is specifically used to: determine the outer wheels and the inner wheels of the vehicle according to the steering intention; if the steering state is an understeering state, then when the target braking force of the outer wheels of the vehicle is greater than the target braking force of the inner wheels of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking conditions; if the steering state is an oversteering state, then when the target braking force of the outer wheels of the vehicle is less than the target braking force of the inner wheels of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking conditions.

[0131] It should be noted that the aforementioned explanation of the steering control method embodiment is also applicable to the steering control device of this embodiment, and will not be repeated here.

[0132] In this embodiment, the functional modules of the device can be divided according to the above method example. For example, each functional module can be corresponded, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware. It should be noted that the division of modules in this embodiment is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0133] It should be understood that the steering control device provided in this embodiment is used to execute the above-mentioned steering control method, and thus can achieve the same effect as the above-mentioned implementation method, which will not be described in detail here.

[0134] The embodiment of the present application also provides a vehicle, Figure 8 is a schematic diagram of the structure of a vehicle provided in an embodiment of the present application, such as Figure 8 As shown, the vehicle may include a memory 801, a processor 802 and a communication interface 803, wherein the communication interface 803 is used for communication between the memory 801 and the processor 802, the memory 801 stores executable program code, and the processor 802 is used to call and execute the executable program code to execute the steering control method provided in the embodiment of the present application.

[0135] This embodiment also provides a computer-readable storage medium, in which a computer program code is stored. When the computer program code is executed on a computer, the computer executes the above-mentioned related method steps to implement the steering control method provided in the above-mentioned embodiment.

[0136] The computer-readable storage medium provided in this embodiment is used to execute the corresponding method provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding method provided above, which will not be repeated here.

[0137] The above contents are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A steering control method, characterized in that: The vehicle independently controls each wheel based on an electromechanical braking system, wherein the method comprises the following steps: Acquiring a steering wheel angle signal and an actual yaw angle of the vehicle; calculating a target yaw angle of the vehicle according to the turning angle signal, and determining a steering state of the vehicle according to the actual yaw angle and the target yaw angle; and Based on the steering state, a target braking force corresponding to each wheel of the vehicle is calculated, and the electronic mechanical braking system is driven to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

2. The method according to claim 1, characterized in that When driving the electronic mechanical braking system to apply the corresponding target braking force to each wheel, the method further includes: calculating a difference between the actual yaw angle and the target yaw angle; Based on the difference, determining the target torque of the drive motor from a preset drive motor torque calibration table; If the current vehicle speed is greater than the preset vehicle speed, the current torque of the drive motor is reduced to the target torque according to the preset torque reduction strategy; otherwise, the current torque of the drive motor is increased to the target torque according to the preset torque increase strategy.

3. The method according to claim 2, characterized in that The calculating, based on the steering state, a target braking force corresponding to each wheel of the vehicle comprises: Obtaining the current brake pedal opening, current brake disc temperature and current vehicle speed of the vehicle; Based on the steering state, the target braking force corresponding to each wheel is calculated according to the current vehicle speed, the current brake pedal opening, the current brake disc temperature, the current vehicle state and the current target yaw angle.

4. The method according to claim 3, characterized in that The determining the steering state of the vehicle according to the actual yaw angle and the target yaw angle comprises: calculating a first difference between the target yaw angle and the actual yaw angle, and determining whether the first difference is greater than a first threshold value; If the first difference is greater than the first threshold value, it is determined that the steering state is an understeering state.

5. The method according to claim 4, characterized in that The determining the steering state of the current vehicle according to the actual yaw angle and the target yaw angle further includes: calculating a second difference between the actual yaw angle and the target yaw angle, and determining whether the second difference is greater than a second threshold value; If the second difference is greater than a second threshold value, the steering state is determined to be an oversteering state.

6. The method according to claim 5, characterized in that After calculating the target braking force corresponding to each wheel of the vehicle based on the steering state, the method further includes: obtaining a steering intention of the vehicle; Based on the steering state and the steering intention, determining whether the target braking force corresponding to each wheel meets a preset braking condition; If the target braking force corresponding to each wheel meets the preset braking condition, the electronic mechanical braking system is allowed to be driven to control the caliper motor corresponding to each wheel to apply the corresponding target braking force to each wheel, so that the vehicle completes the steering action.

7. The method according to claim 6, characterized in that The obtaining of the turning intention of the vehicle comprises: Obtaining the current turn signal on state of the vehicle; The turning intention of the vehicle is determined according to the current turn signal on state.

8. The method according to claim 7, characterized in that The determining, based on the steering state and the steering intention, whether the target braking force corresponding to each wheel satisfies a preset braking condition includes: determining the outer wheel of the vehicle and the inner wheel of the vehicle according to the steering intention; If the steering state is an understeering state, when the target braking force of the outer wheel of the vehicle is greater than the target braking force of the inner wheel of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking condition; If the steering state is an oversteering state, then when the target braking force of the outer wheel of the vehicle is less than the target braking force of the inner wheel of the vehicle, it is determined that the target braking force corresponding to each wheel meets the preset braking condition.

9. A vehicle, characterized in that: The vehicle comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steering control method according to 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, and when the computer program is executed, the steering control method according to any one of claims 1 to 8 is implemented.

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