Steering-braking cooperative control method, system and equipment during brake-by-wire failure

Abstract

The invention relates to the technical field of vehicle control, and discloses a steering-braking cooperative control method, system and equipment during brake-by-wire failure, and the method comprises the steps that running state information of a vehicle is acquired; on the basis of the running state information, whether electronic mechanical brake wheels fail or not is judged; if yes, the braking force deviation of the failed wheel is determined according to the running state information; yawing moment deviation is generated according to the braking force deviation; generating a feed-forward compensation rotation angle based on the yawing moment deviation; determining a feedback compensation rotation angle according to the operation state information; and generating a steering compensation angle for steer-by-wire based on the feedforward compensation rotation angle and the feedback compensation rotation angle. The control system has the beneficial effect that the safety performance and the control reliability of the whole vehicle are improved.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and in particular to steering-braking coordinated control methods, systems and devices in the event of brake-by-wire failure. Background Technology

[0002] Braking-by-wire systems mainly include two technical approaches: electro-hydraulic braking (EHB) and electro-mechanical braking (EMB). Among these, EMB systems represent a significant future development direction for braking-by-wire systems. However, a prominent issue with EMB systems is their high dependence on electrical and communication systems, posing a risk of single-point failure. When the EMB actuator of a particular wheel fails, it can lead to abnormal braking force on that wheel, resulting in uneven distribution of braking force between the left and right sides of the vehicle. This can generate unexpected yaw moments, causing the vehicle to deviate from the driver's intended trajectory, potentially leading to safety hazards such as brake drift or even instability. Summary of the Invention

[0003] This application provides a steering-braking coordinated control method, system, and device for brake-by-wire failure, which solves the technical problem of how to quickly and accurately compensate for unexpected yaw moments, thereby improving the overall vehicle stability.

[0004] To achieve the above objectives, the main technical solutions adopted in this application include:

[0005] In a first aspect, embodiments of this application provide a steering-braking coordinated control method for brake-by-wire failure. The method includes: acquiring vehicle operating status information; determining, based on the operating status information, whether an electromechanical brake wheel has failed; if so, determining the braking force deviation of the failed wheel based on the operating status information; generating a yaw moment deviation based on the braking force deviation; generating a feedforward compensation angle based on the yaw moment deviation; determining a feedback compensation angle based on the operating status information; and generating a steering compensation angle for brake-by-wire based on the feedforward compensation angle and the feedback compensation angle.

[0006] The steering-braking coordinated control method proposed in this application for brake-by-wire failure can promptly detect single or multiple wheel failures in electromechanical braking by acquiring real-time vehicle operating status information. When brake failure occurs, it accurately calculates the braking force deviation and the resulting yaw moment deviation, and generates a steering compensation angle combining feedforward and feedback based on this. Through dynamic coordinated control of the steering-by-wire system, it effectively counteracts the unexpected yaw moment caused by braking force imbalance, thereby maintaining vehicle stability, preventing steering deviation or loss of control, and improving the overall vehicle safety and handling reliability.

[0007] Optionally, the operating status information includes the communication status of the brake actuator of the failed wheel, the actual braking force feedback value, the target braking force, the angular acceleration, and the average angular acceleration of the healthy wheel. Based on the operating status information, the braking force deviation of the failed wheel is determined, including: if the communication status of the brake actuator of the failed wheel is normal and the actual braking force feedback value is valid, then the braking force deviation of the failed wheel is determined based on the actual braking force feedback value and the target braking force; if the communication status of the brake actuator of the failed wheel is abnormal or the actual braking force feedback value is invalid, then the braking force deviation of the failed wheel is determined based on the angular acceleration of the failed wheel and the average angular acceleration of the healthy wheel.

[0008] The calculation path for braking force deviation is intelligently switched by monitoring the communication status of the brake actuator and the validity of the actual braking force feedback value. When the communication status of the brake actuator of the failed wheel is normal and the actual braking force feedback value is valid, accuracy is ensured by directly calculating the difference between the actual braking force and the target braking force. When the communication status of the brake actuator of the failed wheel is abnormal or the actual braking force feedback value is invalid, continuity is ensured by indirectly estimating the difference between the angular acceleration of the failed wheel and the healthy wheel. This achieves accurate and uninterrupted sensing of the braking force deviation of the failed wheel under all working conditions, providing reliable input for subsequent yaw stability compensation control and improving the robustness and reliability of braking force deviation calculation.

[0009] Optionally, if valid data is continuously received from the brake actuator of the failed wheel within a preset time, the communication status of the brake actuator is determined to be normal; otherwise, the communication status of the brake actuator is determined to be abnormal. If the difference between the actual braking force feedback value and the target braking force of the failed wheel is within a specified threshold range, the actual braking force feedback value is determined to be valid; otherwise, the actual braking force feedback value is determined to be invalid.

[0010] By combining communication timeout detection with data rationality verification, the system accurately distinguishes between two core fault modes: actuator performance degradation and complete disconnection. This provides an accurate basis for subsequent braking force deviation calculations, thereby avoiding the risk of miscontrol due to incorrect data input and improving the robustness of the entire collaborative control system.

[0011] Optionally, generating a yaw moment deviation based on the braking force deviation includes: calculating a first product of the half-track of the axle where the failed wheel is located and the braking force deviation, and using the first product as the yaw moment deviation.

[0012] By multiplying the braking force deviation by half the wheel track, the braking force deviation is converted into a yaw moment deviation that causes the vehicle to rotate, providing a precise input for the calculation of the feedforward compensation angle and ensuring the accuracy and effectiveness of subsequent control commands.

[0013] Optionally, generating a feedforward compensation angle based on the yaw moment deviation includes: calculating a second product of the yaw moment deviation and a correction coefficient; calculating a third product of the tire lateral stiffness of the failed wheel and the cosine of the vehicle wheelbase and the vehicle center of gravity sideslip angle; calculating the ratio of the second product to the third product, and using the ratio as the feedforward compensation angle.

[0014] By using feedforward control, a feedforward compensation angle is quickly and proactively generated to counteract the disturbing yaw moment caused by braking force imbalance as soon as possible. This greatly improves the system's response speed and avoids the adjustment lag and oscillation that may result from relying solely on feedback control, providing crucial and timely initial compensation for maintaining vehicle stability.

[0015] Optionally, determining the feedback compensation angle based on the operating status information includes: determining the target yaw rate and the actual yaw rate based on the operating status information; and calculating the feedback compensation angle using a PID algorithm based on the deviation between the target yaw rate and the actual yaw rate.

[0016] By calculating the yaw rate deviation between the driver's desired target yaw rate and the vehicle's actual yaw rate in real time, and using a PID controller for precise and continuous closed-loop adjustment, the steady-state error and external disturbances that feedforward control could not fully compensate for can be effectively eliminated, ensuring that the vehicle's yaw motion always accurately tracks the driver's steering intention. Through the complementary advantages of feedback control and feedforward control, a rapid-response and precise collaborative control system is formed, enhancing the vehicle's stability and safety under failure conditions.

[0017] Optionally, the operating status information may also include the steering wheel angle and vehicle speed, and the method may further include: calculating the target yaw rate based on the steering wheel angle and vehicle speed.

[0018] By inputting the two core parameters that directly reflect the driver's intention and the vehicle's state—steering wheel angle and vehicle speed—into a validated vehicle dynamics model, the target yaw rate is calculated in real time. This quantifies the driver's subjective and vague steering expectations into objective and precise vehicle motion target values, providing an important benchmark reference for the entire cooperative control system. This enables the system to clearly determine whether the vehicle's current actual state deviates from the driver's expectations, which is conducive to achieving precise and reliable stability control.

[0019] Optionally, generating a steering compensation angle for steer-by-wire based on the feedforward compensation angle and the feedback compensation angle includes: adding the feedforward compensation angle and the feedback compensation angle to obtain the steering compensation angle.

[0020] By employing feedforward control for rapid and proactive disturbance compensation, and feedback control for precise and continuous closed-loop adjustment, the steady-state accuracy and robustness of the control are ensured. Adding the feedforward compensation angle and the feedback compensation angle results in a final output steering compensation angle that can both quickly respond to severe disturbances caused by braking force imbalance and accurately eliminate steady-state deviations caused by feedforward model errors and external disturbances, thereby improving the dynamic performance of vehicle stability control.

[0021] Secondly, embodiments of this application provide a steering-braking coordinated control system for when brake-by-wire fails. The system includes: an acquisition module for acquiring vehicle operating status information; a feedforward module for determining, based on the operating status information, whether an electromechanical brake wheel has failed; if so, determining the braking force deviation of the failed wheel based on the operating status information; generating a yaw moment deviation based on the braking force deviation; generating a feedforward compensation angle based on the yaw moment deviation; a feedback module for determining a feedback compensation angle based on the operating status information; and a steering module for generating a steering compensation angle for steer-by-wire based on the feedforward compensation angle and the feedback compensation angle.

[0022] Thirdly, embodiments of this application provide a computer device, including: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the above-mentioned steering-braking coordinated control method when brake-by-wire fails.

[0023] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer instructions, which are used to cause a computer to execute the above-described steering-braking coordinated control method when brake-by-wire fails.

[0024] Fifthly, embodiments of this application provide a computer program product, including computer instructions, which are used to cause a computer to execute the above-described steering-braking coordinated control method when brake-by-wire fails. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This embodiment provides a flowchart of a steering-braking coordinated control method for brake-by-wire failure.

[0027] Figure 2 A schematic diagram of a steering-braking coordinated control system in the event of brake-by-wire failure, provided in an embodiment of this application.

[0028] Figure 3 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] With the rapid development of automotive electronics and intelligent technologies, brake-by-wire (BBW) systems are increasingly widely used in vehicles. BBW systems mainly include two technical routes: electro-hydraulic brake (EHB) and electro-mechanical brake (EMB). Among them, the EMB system abandons traditional hydraulic lines and uses a motor to directly drive the brake caliper, offering advantages such as fast response, high control precision, and compact structure, representing an important future development direction for brake-by-wire systems. However, EMB systems also face certain technical challenges. A prominent issue is their high dependence on electrical and communication systems, posing a risk of single-point failure. When the EMB actuator of a particular wheel fails due to abnormal power supply, motor jamming, communication interruption, or control circuit malfunction, it can lead to abnormal braking force on that wheel (such as insufficient or complete loss of braking force), causing uneven distribution of braking force between the left and right sides of the vehicle, generating unexpected yaw moments, and causing the vehicle to deviate from the driver's intended driving trajectory, thus leading to safety hazards such as brake drift or even instability. To address the aforementioned issues, relevant technologies primarily focus on maintaining vehicle stability through fault-tolerant control of the braking system itself. Typical methods include redistributing braking force to the unaffected wheels or transferring braking force between axles to compensate for the braking imbalance caused by a single wheel failure. However, these solutions relying solely on the braking system for compensation have significant limitations: firstly, the braking force redistribution process may lead to a decrease in the total braking force of the vehicle, increasing the braking distance; secondly, under low-friction road conditions, the available adhesion of healthy wheels is limited, making it difficult to generate sufficient compensating yaw moment through differential braking, still failing to effectively suppress vehicle deviation, and potentially even increasing the risk of fishtailing due to excessive distribution of braking force to the rear axle. Therefore, how to quickly and stably compensate for unexpected yaw moments in the event of single or multiple wheel failure in the online braking system, without over-reliance on the braking system, and ensure that the vehicle travels as intended by the driver, has become a pressing technical problem to be solved in this field.

[0031] This application provides a steering-braking coordinated control method when brake-by-wire fails. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although the logical order is shown in the flowchart, in some cases the steps shown or described can be executed in a different order than that shown here.

[0032] Please refer to Figure 1 , Figure 1 This embodiment provides a flowchart of a steering-braking coordinated control method for brake-by-wire failure, as shown below. Figure 1 As shown, the process includes the following steps:

[0033] S100, obtain vehicle operating status information.

[0034] The operational status information can be used to determine the vehicle's status in real time. This operational status information includes, but is not limited to: wheel speeds directly measured by wheel speed sensors, and a reference vehicle speed calculated based on these wheel speeds; vehicle yaw rate directly measured by an inertial measurement unit (IMU); steering wheel angle directly measured by a steering wheel angle sensor; drive torque provided by the vehicle control unit (VCU); actual braking force feedback values ​​for each wheel; and target braking force, etc.

[0035] S300, based on the operating status information, determine whether an electromechanical brake wheel has failed; if so, determine the braking force deviation of the failed wheel according to the operating status information; generate a yaw moment deviation according to the braking force deviation; and generate a feedforward compensation angle based on the yaw moment deviation.

[0036] Electromechanical brake wheel failure refers to the state where the brake actuator of a certain EMB wheel fails to provide the expected braking force due to a malfunction. Such malfunctions include, but are not limited to, abnormal actuator power supply, interruption of control signal communication, motor jamming, or control circuit failure. Data such as wheel speeds, target braking forces, actual braking force feedback values, and steering wheel angle from the operational status information can provide a basis for determining electromechanical brake wheel failure and identifying the failed wheel. Braking force deviation refers to the difference between the actual braking force and the target braking force of the failed wheel. Yaw moment deviation is the torque caused by the braking force deviation, resulting in the vehicle rotating around its vertical axis. Feedforward compensation steering angle is used for rapid response to counteract yaw moment deviation, applying compensation at the moment of wheel failure to prevent vehicle veer.

[0037] S500, based on the operating status information, determines the feedback compensation angle.

[0038] Among them, the feedback compensation angle is used to continuously correct the deviation between the vehicle's actual yaw rate and the driver's expected target yaw rate, ensuring that the vehicle can ultimately travel stably and accurately along the path expected by the driver.

[0039] S700, based on the feedforward compensation angle and the feedback compensation angle, generates a steering compensation angle for steer-by-wire.

[0040] The feedforward compensation angle obtained from the feedforward control is used for coarse adjustment, and the feedback compensation angle is used for fine adjustment. The coarse and fine adjustments are combined to generate the steering compensation angle, which is then input into the Steer By Wire (SBW) system to control the steering and compensate for vehicle instability caused by brake failure.

[0041] By acquiring real-time vehicle operating status information, it is possible to promptly detect single or multiple wheel failures in electromechanical braking. In the event of brake failure, the system accurately calculates the braking force deviation and the resulting yaw moment deviation, and generates a steering compensation angle combining feedforward and feedback based on this. Dynamic coordinated control through the steer-by-wire system effectively counteracts the unexpected yaw moment caused by braking force imbalance, thereby maintaining vehicle stability, preventing steering deviation or loss of control, and improving overall vehicle safety and handling reliability.

[0042] In some embodiments, the operating status information includes the communication status of the brake actuator of the failed wheel, the actual braking force feedback value, the target braking force, the angular acceleration, and the average angular acceleration of the healthy wheel. Determining the braking force deviation of the failed wheel based on the operating status information includes: if the communication status of the brake actuator of the failed wheel is normal and the actual braking force feedback value is valid, then determining the braking force deviation of the failed wheel based on the actual braking force feedback value and the target braking force; if the communication status of the brake actuator of the failed wheel is abnormal or the actual braking force feedback value is invalid, then determining the braking force deviation of the failed wheel based on the angular acceleration of the failed wheel and the average angular acceleration of the healthy wheel.

[0043] When an electromechanical brake wheel fails, there are two scenarios: one is that the brake actuator of the failed wheel has a normal communication status and the actual braking force feedback value is valid; the other is that the brake actuator of the failed wheel has an abnormal communication status or the actual braking force feedback value is invalid.

[0044] If the brake actuator of the failed wheel is in normal communication mode and the actual braking force feedback value is valid, the failure is due to a problem with the brake actuator's motor or transmission mechanism (such as jamming or slippage), causing the wheel to fail to output the desired target braking force. Meanwhile, the failed wheel's own sensors and communication circuits are functioning normally, and the actual braking force feedback value measured by the sensors is valid and reliable. Therefore, the braking force deviation can be obtained directly from the difference between the actual braking force and the target braking force.

[0045] When the brake actuator of the failed wheel experiences abnormal communication or invalid actual braking force feedback, the failure is likely due to an interruption in the brake actuator's power supply, control circuit, or communication line, preventing the wheel from outputting the desired target braking force, or a faulty sensor rendering the measured actual braking force feedback invalid. Since the actual braking force cannot be directly determined, it can only be estimated indirectly by comparing the difference in angular acceleration between the failed wheel and the healthy wheel to infer the residual braking force of the failed wheel.

[0046] The calculation path for braking force deviation is intelligently switched by monitoring the communication status of the brake actuator and the validity of the actual braking force feedback value. When the communication status of the brake actuator of the failed wheel is normal and the actual braking force feedback value is valid, accuracy is ensured by directly calculating the difference between the actual braking force and the target braking force. When the communication status of the brake actuator of the failed wheel is abnormal or the actual braking force feedback value is invalid, continuity is ensured by indirectly estimating the difference between the angular acceleration of the failed wheel and the healthy wheel. This achieves accurate and uninterrupted sensing of the braking force deviation of the failed wheel under all working conditions, providing reliable input for subsequent yaw stability compensation control and improving the robustness and reliability of braking force deviation calculation.

[0047] In some specific embodiments, when the brake actuator of the failed wheel is in normal communication status and the actual braking force feedback value is valid, the formula for calculating the braking force deviation ΔF of the failed wheel is as follows:

[0048] ΔF=F act –F tar

[0049] In the above formula, F tar For the target braking force of the failed wheel, F act This represents the actual braking force of the failed wheel.

[0050] When the brake actuator of the failed wheel has an abnormal communication status or the actual braking force feedback value is invalid, the formula for calculating the braking force deviation ΔF of the failed wheel is as follows:

[0051]

[0052] In the above formula, J is the moment of inertia of the failed wheel (kg·m). 2 ), is a constant, which can be obtained through testing; ω fail The angular velocity of the failed wheel can be calculated based on the wheel speed sensor signal; ω heelthy The average angular velocity of the healthy wheel can be calculated based on the wheel speed sensor signal; T roll T represents the rolling resistance torque of the wheel, expressed in Nm. It is a constant and its final value can be determined using calibration methods. drive T represents the driving torque on the wheels, measured in Nm, under braking conditions. drive =0, T drive This signal can be obtained via the CAN bus and is provided by the vehicle controller; wheel This is the rolling radius of the wheel.

[0053] When an EMB wheel fails, the braking force deviation of the failed wheel can be inferred by comparing the difference between the angular acceleration of the failed wheel and that of the other healthy wheels, and by subtracting the corresponding driving torque and rolling resistance.

[0054] The sign of the braking force deviation ΔF is defined as follows: under braking conditions, ΔF is positive when the left wheel fails and negative when the right wheel fails; under non-braking conditions, ΔF is negative when the left wheel fails and positive when the right wheel fails.

[0055] By defining the signs of braking force deviation in opposite ways under braking and non-braking conditions, a unified mathematical description of the vehicle instability direction is achieved. The sign of the braking force deviation ΔF can accurately identify the vehicle's yaw trend, thus laying a consistent logical foundation for generating the correct steering compensation angle and preventing control logic confusion or incorrect compensation direction due to differences in operating conditions.

[0056] In some embodiments, if valid data is continuously received from the brake actuator of the failed wheel within a preset time, the communication status of the brake actuator is determined to be normal; otherwise, the communication status of the brake actuator is determined to be abnormal. If the difference between the actual braking force feedback value and the target braking force of the failed wheel is within a specified threshold range, the actual braking force feedback value is determined to be valid; otherwise, the actual braking force feedback value is determined to be invalid.

[0057] If valid data packets are continuously received within the preset time window, it indicates that the communication link is working properly and the brake actuator of the failed wheel is under control. Conversely, if no data is received within the time limit, it indicates that the communication is interrupted or the brake actuator has completely failed. The difference between the actual braking force and the target braking force is calculated. This difference is compared with a specified threshold range. If the difference is within the specified threshold range, it indicates that the data conforms to physical laws and the sensor is working properly, and the actual braking force feedback value is determined to be valid. If the difference deviates significantly from the specified threshold, it indicates that the sensor is faulty, the signal transmission is incorrect, or the data is severely distorted, and the actual braking force feedback value is determined to be invalid. This eliminates abnormal data interference and ensures the safety and accuracy of subsequent decision-making and execution.

[0058] In some embodiments, generating a yaw moment deviation based on the braking force deviation includes: calculating a first product of the half-track of the axle where the failed wheel is located and the braking force deviation, and using the first product as the yaw moment deviation.

[0059] Specifically, the formula for calculating the yaw moment deviation ΔMz is as follows:

[0060] ΔMz=ΔF×d

[0061] In the above formula, ΔF represents the braking force deviation, and d represents half the wheel track, in meters (m). Half the wheel track refers to half the lateral distance between the center points of the left and right wheels on the axle where the failed wheel is located.

[0062] By multiplying the braking force deviation by half the wheel track, the braking force deviation is converted into a yaw moment deviation that causes the vehicle to rotate, providing a precise input for the calculation of the feedforward compensation angle and ensuring the accuracy and effectiveness of subsequent control commands.

[0063] In some embodiments, generating a feedforward compensation angle based on the yaw moment deviation includes: calculating a second product of the yaw moment deviation and a correction coefficient; calculating a third product of the tire lateral stiffness of the failed wheel and the cosine of the vehicle wheelbase and the vehicle center of gravity sideslip angle; calculating the ratio of the second product to the third product, and using the ratio as the feedforward compensation angle.

[0064] The correction coefficient (usually denoted as K) is determined through actual testing and calibration, and is used to compensate for the deviation between the theoretical model and the actual vehicle dynamic characteristics. By testing and repeatedly adjusting the K value under a series of conditions, including different vehicle speeds, loads, and road surface adhesion coefficients (such as high-adhesion asphalt roads and low-adhesion ice surfaces), the feedforward compensation steering angle achieves optimal compensation results in various scenarios. Ultimately, the K value forms a two-dimensional lookup table based on the reference vehicle speed and road surface adhesion coefficient, which can be accessed in real time.

[0065] Tire lateral stiffness characterizes a tire's ability to generate lateral forces, and its characteristic curve is obtained through testing on a tire test bench. Vehicle wheelbase refers to the horizontal distance between the centers of the front and rear axles. Vehicle center-of-gravity sideslip angle is a dynamic estimate, calculated in real-time by measuring the vehicle's lateral acceleration and lateral velocity using an onboard inertial measurement unit, combined with the longitudinal velocity calculated from wheel speed sensors.

[0066] To counteract the yaw moment deviation, a yaw moment of equal magnitude but opposite direction is needed. This is achieved by generating a lateral force on the tires, thus creating a counter-yaw moment. Since the vehicle's sideslip angle is very small and approximately proportional to the steering angle, a simplified transfer function can be derived to "map" the counter-yaw moment to the desired steering angle. Specifically, the feedforward compensation steering angle δ... FF The calculation formula is as follows:

[0067]

[0068] In the above formula, K is the correction coefficient; ΔMz is the yaw moment deviation; C is the lateral stiffness of the failed wheel, in N / rad; L is the vehicle wheelbase, in m; β is the vehicle center of gravity sideslip angle, in degrees. V y (Vehicle lateral speed) and V x (Vehicle longitudinal speed) is calculated based on the inertial measurement unit and wheel speed sensor, respectively.

[0069] By using feedforward control, a feedforward compensation angle is quickly and proactively generated to counteract the disturbing yaw moment caused by braking force imbalance as soon as possible. This greatly improves the system's response speed and avoids the adjustment lag and oscillation that may result from relying solely on feedback control, providing crucial and timely initial compensation for maintaining vehicle stability.

[0070] In some embodiments, determining the feedback compensation angle based on the operating status information includes: determining the target yaw rate and the actual yaw rate based on the operating status information; and calculating the feedback compensation angle using a PID algorithm based on the deviation between the target yaw rate and the actual yaw rate.

[0071] The target yaw rate characterizes the driver's desired vehicle motion state and reflects the driver's steering intention. Using a two-degree-of-freedom vehicle model, the driver's steering intention can be quantified as the target yaw rate. The actual yaw rate characterizes the vehicle's actual motion state. The actual yaw rate is directly measured by the onboard inertial measurement unit and is considered operational status information. Due to braking imbalance, the actual yaw rate will deviate from the target yaw rate, causing the vehicle to veer off course. A PID algorithm is used to obtain the final feedback compensation steering angle to eliminate the deviation between the target and actual yaw rates.

[0072] Specifically, the feedback compensation angle δ is calculated using a PID algorithm. FB The formula is as follows:

[0073]

[0074] Where e is the deviation between the target yaw rate and the actual yaw rate, in rad / s; K p K i K d These are the proportional, integral, and differential coefficients, respectively.

[0075] The formula for calculating the deviation e between the target yaw rate and the actual yaw rate is as follows:

[0076] e = Yaw tgt -Yaw act

[0077] In the above formula, Yaw tgt The target yaw rate desired by the driver can be calculated using the following formula for a two-degree-of-freedom vehicle model:

[0078]

[0079] In the above formula, V ref For reference vehicle speed, the unit is m / s; L is the vehicle wheelbase, the unit is m; StrAngle Steering wheel angle, unit: rad; Str Ratio The steering gear ratio is Vch, and the characteristic vehicle speed is Vch, obtained through testing, in m / s; Yaw act The actual yaw rate of the vehicle is obtained by measuring and filtering using an inertial measurement unit.

[0080] By calculating the yaw rate deviation between the driver's desired target yaw rate and the vehicle's actual yaw rate in real time, and using a PID controller for precise and continuous closed-loop adjustment, the steady-state error and external disturbances that feedforward control could not fully compensate for can be effectively eliminated, ensuring that the vehicle's yaw motion always accurately tracks the driver's steering intention. Through the complementary advantages of feedback control and feedforward control, a rapid-response and precise collaborative control system is formed, enhancing the vehicle's stability and safety under failure conditions.

[0081] In some embodiments, the operating status information further includes steering wheel angle and vehicle speed, and the method further includes: calculating the target yaw rate based on the steering wheel angle and vehicle speed.

[0082] By inputting the two core parameters that directly reflect the driver's intention and the vehicle's state—steering wheel angle and vehicle speed—into a validated vehicle dynamics model, the target yaw rate is calculated in real time. This quantifies the driver's subjective and vague steering expectations into objective and precise vehicle motion target values, providing an important benchmark reference for the entire cooperative control system. This enables the system to clearly determine whether the vehicle's current actual state deviates from the driver's expectations, which is conducive to achieving precise and reliable stability control.

[0083] In some embodiments, generating a steering compensation angle for steer-by-wire based on the feedforward compensation angle and the feedback compensation angle includes: adding the feedforward compensation angle and the feedback compensation angle to obtain the steering compensation angle.

[0084] Specifically, the steering compensation angle δ comp The calculation formula is as follows:

[0085] δ comp =δ FF +δ FB

[0086] In the above formula, δ FF For feedforward compensation angle; δ FB To provide feedback and compensation for corner turns.

[0087] The steering compensation angle is defined as negative for left turns and positive for right turns. By defining the sign of the steering compensation angle, it is coordinated with the aforementioned braking force deviation to ensure that a compensation torque in the correct direction is generated to counteract yaw deviation and maintain vehicle stability.

[0088] By employing feedforward control for rapid and proactive disturbance compensation, and feedback control for precise and continuous closed-loop adjustment, the steady-state accuracy and robustness of the control are ensured. Adding the feedforward compensation angle and the feedback compensation angle results in a final output steering compensation angle that can both quickly respond to severe disturbances caused by braking force imbalance and accurately eliminate steady-state deviations caused by feedforward model errors and external disturbances, thereby improving the dynamic performance of vehicle stability control.

[0089] In some embodiments, if there are multiple failed wheels, the steering compensation angle corresponding to each failed wheel is calculated separately, and then the steering compensation angles of each failed wheel are algebraically added together to obtain the final total compensation angle, which is then sent to the steer-by-wire system for execution.

[0090] For example, if the left front wheel (FL) fails, it requires turning -10° to the left to compensate; if the right rear wheel (RR) fails, it requires turning +7° to the right to compensate. The system will then ultimately request to execute -10° + 7° = -3° (i.e., turn 3° to the left). This combined instruction will compensate for the effects of both failed wheels simultaneously.

[0091] In some embodiments, the feedforward compensation angle and the feedback compensation angle are added together to obtain the steering compensation angle. The steering compensation angle is then superimposed on the driver's current steering wheel angle to obtain the total steering compensation angle executed by the steer-by-wire system.

[0092] By optimizing stability based on the driver's intentions, the system ensures that the vehicle does not veer off course while maximizing the driver's control.

[0093] For example, if the driver's current steering wheel angle is -90° (90 degrees left turn) and the steering compensation angle is -15° (15 degrees left turn), then the total steering compensation angle executed by the steer-by-wire system is -105° (105 degrees left turn). As another example, if the driver's current steering wheel angle is -90° (90 degrees left turn) and the steering compensation angle is +15° (15 degrees right turn), then the total steering compensation angle executed by the steer-by-wire system is -75° (75 degrees left turn).

[0094] The following will describe the specific implementation details.

[0095] Example 1

[0096] In this embodiment, under braking conditions, the left rear wheel (RL wheel) fails, resulting in insufficient braking force. Its brake actuator communication status is normal, and the actual braking force feedback value is valid. The driver intends to turn left, with a steering wheel angle of -0.2 rad. The actual yaw rate is -0.15 rad / s, indicating that the vehicle is yawing to the right, suggesting that the vehicle is beginning to lose stability due to the failure of the left rear wheel. The current vehicle speed is 20 m / s. The target braking forces (in N) for the four wheels are as follows: front left wheel (FL wheel) -12000; front right wheel (FR wheel) 12000; rear left wheel (RL wheel) -8000; rear right wheel (RR wheel) -8000. The actual braking force feedback values ​​(in N) of the four wheels of the vehicle are as follows: front left wheel (FL wheel) -12000; front right wheel (FR wheel) 12000; rear left wheel (RL wheel) -1000; rear right wheel (RR wheel) -8000.

[0097] It can be seen that the actual braking force feedback value of the left rear wheel (RL) is much smaller than its target braking force, indicating a serious lack of braking force.

[0098] The steering-braking coordinated control method for brake-by-wire failure provided in this application specifically includes the following calculation process:

[0099] 1) Calculate the braking force deviation. Since the braking force of the RL wheel is insufficient, the braking force deviation ΔF is defined as positive, and its calculation formula is:

[0100] ΔF=F act -F tar =-1000-(-8000)=7000N

[0101] The half wheel track d is 1.5m, and the yaw moment deviation ΔMz is: ΔMz=ΔF×d=7000×1.5=10500Nm.

[0102] 2) Calculate the feedforward compensation angle. Through calibration and table lookup, the correction coefficient K is found to be 1.2, the tire lateral stiffness is 40000 N / rad, and β is approximately equal to 0.

[0103]

[0104] 3) Calculate the feedback compensation angle.

[0105] The driver's desired target yaw rate is:

[0106]

[0107] Among them, the characteristic vehicle speed Vch is 30m / s, the vehicle wheelbase L is 2.7m, and the steering ratio Str Ratio It is 16.

[0108] The deviation between the target yaw rate and the actual yaw rate is:

[0109] e = Yaw tgt -Yaw act =0.175-(-0.15)=0.325rad / s

[0110] In the PID algorithm, K p K i K d The values ​​are 0.8, 0.2, and 0.3, respectively.

[0111] Feedback compensation angle is:

[0112]

[0113] 4) The final steering compensation angle is:

[0114] δ comp =δ FF +δ FB =6.7° + 15.64° = 22.34°

[0115] Example 2

[0116] In this embodiment, under non-braking conditions, the right front wheel (FR wheel) fails, its brake actuator communication status is abnormal or the actual braking force feedback value is invalid, making it impossible to directly read the braking force data of the failed wheel. The driver intends the vehicle to travel in a straight line, with a steering wheel angle of 0 rad. The actual yaw rate is -0.1 rad / s, indicating that the vehicle is yawing to the right. With a steering wheel angle of 0, the vehicle automatically veers to the right, indicating that the vehicle has become unstable. The current vehicle speed is 10 m / s. The angular acceleration of the vehicle's four wheels (in rad / s²) is also shown. 2 The values ​​are as follows: front left wheel (FL wheel) is 10; front right wheel (FR wheel) is -15; rear left wheel (RL wheel) is 11; rear right wheel (RR wheel) is 10.5.

[0117] This means that while other wheels are accelerating normally or moving at a constant speed, the right front wheel is decelerating violently. This indicates that there is a large, uninstructed residual braking force on the right front wheel (such as a dragging torque caused by jamming).

[0118] The steering-braking coordinated control method for brake-by-wire failure provided in this application specifically includes the following calculation process:

[0119] 1) Calculate the braking force deviation ΔF of the failed wheel. The average angular velocity of the healthy wheel is:

[0120]

[0121] Wherein, the moment of inertia J = 1.2 kg·m 2 Rolling torque Troll = 5 Nm, rolling radius = 0.35, wheel end output torque T drive The value is 800 Nm, and the direction of ΔF is defined as negative.

[0122] With a half-track width d of 1.5m, the yaw moment deviation ΔMz is:

[0123] ΔMz=ΔF×d=2184×1.5=3276Nm

[0124] 2) Calculate the feedforward compensation angle. Through calibration and table lookup, the correction coefficient K is found to be 1.5, the tire lateral stiffness is 45000 N / rad, and β is approximately 5°.

[0125]

[0126] 3) Calculate the feedback compensation angle.

[0127] The driver's desired target yaw rate is:

[0128]

[0129] Among them, the characteristic vehicle speed Vch is 30m / s, the vehicle wheelbase L is 2.7m, and the steering ratio Str Ratio It is 16.

[0130] The deviation between the target yaw rate and the actual yaw rate is:

[0131] e = 0 - (-0.1) = 0.1 rad / s.

[0132] In the PID algorithm, K p K i K d The values ​​are 1, 0.8, and 0.5, respectively.

[0133] Feedback compensation angle is:

[0134]

[0135] 4) The final steering compensation angle is:

[0136] δ comp =δ FF +δ FB =2.33° + 7.73° = 10.06°

[0137] Accordingly, please refer to Figure 2 , Figure 2 This is a schematic diagram of the steering-braking coordinated control system in the event of brake-by-wire failure, as provided in an embodiment of this application. Figure 2As shown, the system includes: an acquisition module for acquiring vehicle operating status information; a feedforward module for determining, based on the operating status information, whether any electromechanical brake wheels have failed; if so, determining the braking force deviation of the failed wheel based on the operating status information; generating a yaw moment deviation based on the braking force deviation; generating a feedforward compensation angle based on the yaw moment deviation; a feedback module for determining a feedback compensation angle based on the operating status information; and a steering module for generating a steering compensation angle for steer-by-wire based on the feedforward compensation angle and the feedback compensation angle.

[0138] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0139] In this embodiment, the steering-braking coordinated control system is presented in the form of functional units. Here, a unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0140] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application, such as... Figure 3 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 3 Take a processor 10 as an example.

[0141] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0142] The memory 20 stores instructions executable by at least one processor 10 to cause the at least one processor 10 to perform the method shown in the above embodiments.

[0143] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0144] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0145] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0146] This application also provides a computer-readable storage medium. The methods described in this application can be implemented in hardware or firmware, or implemented as recordable on a storage medium, or implemented as computer code downloaded over a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and subsequently stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the methods shown in the above embodiments are implemented.

[0147] This application provides a computer program product including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the method of any embodiment of this application.

[0148] The systems and modules described in the above embodiments can be implemented by computer chips or physical entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0149] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0150] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0151] This application is described with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0152] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0153] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0154] It should also be noted that 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 process, method, article, or apparatus. Without further limitation, 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.

[0155] 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 its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0156] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0157] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A steering-braking coordinated control method for brake-by-wire failure, characterized in that, The method includes: Obtain vehicle operating status information; Based on the operating status information, determine whether any electromechanical brake wheels have failed; if so, determine the braking force deviation of the failed wheel based on the operating status information; generate a yaw moment deviation based on the braking force deviation; and generate a feedforward compensation angle based on the yaw moment deviation. Based on the aforementioned operating status information, determine the feedback compensation angle; Based on the feedforward compensation angle and the feedback compensation angle, a steering compensation angle for steer-by-wire is generated.

2. The method according to claim 1, characterized in that, The operational status information includes the communication status of the brake actuator of the failed wheel, the actual braking force feedback value, the target braking force, the angular acceleration, and the average angular acceleration of the healthy wheel. Based on the operational status information, the braking force deviation of the failed wheel is determined, including: If the brake actuator of the failed wheel is in normal communication status and the actual braking force feedback value is valid, then the braking force deviation of the failed wheel is determined based on the actual braking force feedback value of the failed wheel and the target braking force. If the brake actuator of the failed wheel has an abnormal communication status or the actual braking force feedback value is invalid, the braking force deviation of the failed wheel is determined based on the angular acceleration of the failed wheel and the average angular acceleration of the healthy wheel.

3. The method according to claim 2, characterized in that, The method further includes: If valid data is continuously received from the brake actuator of the failed wheel within a preset time, the communication status of the brake actuator is determined to be normal; otherwise, the communication status of the brake actuator is determined to be abnormal. If the difference between the actual braking force feedback value and the target braking force of the failed wheel is within a specified threshold range, then the actual braking force feedback value is determined to be valid; otherwise, the actual braking force feedback value is determined to be invalid.

4. The method according to claim 1, characterized in that, Based on the braking force deviation, a yaw moment deviation is generated, including: Calculate the first product of the half wheel track of the axle where the failed wheel is located and the braking force deviation, and use the first product as the yaw moment deviation.

5. The method according to claim 4, characterized in that, Based on the yaw moment deviation, a feedforward compensation angle is generated, including: Calculate the second product of the yaw moment deviation and the correction factor; Calculate the third product of the tire lateral stiffness of the failed wheel with the cosine of the vehicle wheelbase and the lateral slip angle of the vehicle's center of gravity; Calculate the ratio of the second product to the third product, and use the ratio as the feedforward compensation angle.

6. The method according to claim 1, characterized in that, Based on the aforementioned operating status information, the feedback compensation angle is determined, including: Based on the aforementioned operating status information, determine the target yaw rate and the actual yaw rate; The feedback compensation angle is calculated using a PID algorithm based on the deviation between the target yaw rate and the actual yaw rate.

7. The method according to claim 6, characterized in that, The operating status information also includes steering wheel angle and vehicle speed, and the method further includes: The target yaw rate is calculated based on the steering wheel angle and the vehicle speed.

8. The method according to claim 1, characterized in that, Based on the feedforward compensation angle and the feedback compensation angle, a steering compensation angle for steer-by-wire is generated, including: The feedforward compensation angle and the feedback compensation angle are added together to obtain the steering compensation angle.

9. A steering-braking coordinated control system for brake-by-wire failure, characterized in that, The system includes: The acquisition module is used to acquire vehicle operating status information; The feedforward module is used to determine whether an electromechanical brake wheel has failed based on the operating status information; if so, it determines the braking force deviation of the failed wheel based on the operating status information; it generates a yaw moment deviation based on the braking force deviation; and it generates a feedforward compensation angle based on the yaw moment deviation. The feedback module is used to determine the feedback compensation angle based on the operating status information; The steering module is used to generate a steering compensation angle for steer-by-wire based on the feedforward compensation angle and the feedback compensation angle.

10. A computer device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the steering-braking coordinated control method for brake-by-wire failure as described in any one of claims 1 to 8.

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