A method and system for controlling distribution of cornering braking force of a vehicle equipped with an electromechanical brake system

Abstract

The application relates to the technical field of vehicle braking control, and discloses a vehicle turning braking force distribution control method and system loaded with an electronic mechanical braking system. The method comprises the following steps: acquiring real-time state information of a vehicle; performing initial braking force distribution on the vehicle; calculating expected yaw angular velocity and expected mass center side slip angle of the vehicle by adopting a linear two-degree-of-freedom vehicle steady-state model; calculating torque adjustment amounts of the yaw angular velocity and the mass center side slip angle by adopting a torque adjustment controller; dynamically adjusting the torque adjustment amounts of the yaw angular velocity and the mass center side slip angle by adopting an error weight proportion distribution method, so as to obtain expected braking torques needed on the vehicle wheels; calculating slip rate compensation torques of the vehicle wheels by adopting a compensation torque controller; and performing secondary braking force distribution on the vehicle wheels according to the expected braking torques of the vehicle wheels and the slip rate compensation torques of the vehicle wheels. The application can improve the yaw stability of the vehicle in the turning braking process, inhibit side slip and optimize braking efficiency.

Description

Technical Field

[0001] This invention relates to the field of vehicle braking control technology, specifically to a method and system for controlling the distribution of braking force during vehicle cornering, equipped with an electromechanical braking system. Background Technology

[0002] In recent years, with the development of drive-by-wire technology, drive-by-wire braking technology can solve problems such as uneven distribution of braking force, insufficient control precision, and response delay in vehicle braking.

[0003] Existing technologies for braking force distribution during cornering in vehicles equipped with electromechanical braking systems mainly fall into two categories: one is based on vertical load, distributing braking force according to the proportion of vertical load on each wheel; the other is based on multi-objective optimization, distributing braking force to the four wheels by setting an optimization objective function and constraints. The first method first allocates initial braking force based on the proportion of vertical load on each wheel, then adds the braking force required to generate additional yaw moment. In this case, it may lead to wheel lock-up on one side due to over-braking. The second method may fail to simultaneously meet the requirements for braking force and yaw moment, potentially resulting in an unsolvable problem in solving the optimization objective function. Therefore, both methods result in low stability and safety during vehicle operation.

[0004] Existing yaw control strategies primarily rely on simulation studies, lacking comprehensive validation under real-world complex conditions, and most fail to consider the impact of braking system delay on control effectiveness. Therefore, introducing a braking force distribution control strategy based on yaw rate, sideslip angle, and slip ratio to improve braking system stability and braking efficiency is particularly important. This control method can further enhance vehicle yaw stability and control performance under complex driving conditions, thus possessing broad application prospects in handling variable vehicle loads and complex road conditions. Summary of the Invention

[0005] To address the aforementioned shortcomings in the prior art, this invention provides a method and system for controlling the distribution of braking force during vehicle cornering, equipped with an electromechanical braking system. This addresses the problem that the prior art does not consider factors such as large changes in vehicle load and vehicle sideslip and fishtailing during cornering braking, which leads to a severe decline in yaw control performance and an inability to meet vehicle stability control requirements. The invention achieves improved yaw stability, sideslip suppression, and optimized braking performance during vehicle cornering braking.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] In a first aspect, the present invention proposes a method for controlling the distribution of braking force during vehicle cornering, equipped with an electromechanical braking system, comprising the following steps:

[0008] In response to vehicle turning and braking requirements, obtain real-time vehicle status information;

[0009] The initial braking force is distributed to the vehicle based on its longitudinal acceleration.

[0010] Based on the vehicle's longitudinal velocity and steering wheel angle, a linear two-degree-of-freedom vehicle steady-state model is used to calculate the vehicle's desired yaw rate and desired center-of-gravity sideslip angle.

[0011] Based on the vehicle's desired yaw rate and desired sideslip angle, as well as the actual yaw rate and actual sideslip angle, a torque adjustment controller is used to calculate the torque adjustment amount for the yaw rate and the torque adjustment amount for the sideslip angle.

[0012] The torque adjustment of yaw rate and the torque adjustment of center of gravity sideslip angle are dynamically adjusted by using the error weight ratio allocation method to obtain the desired braking torque to be applied to the wheel.

[0013] Based on the vehicle speed and wheel rotation speed, a compensation torque controller is used to calculate the slip ratio compensation torque for each wheel;

[0014] The desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel are used to perform secondary braking force distribution to each wheel of the vehicle.

[0015] Furthermore, the initial braking force distribution to the vehicle based on its longitudinal acceleration includes:

[0016] The vertical load of each wheel is calculated based on the longitudinal lateral acceleration, and the proportion of the vertical load of each wheel is calculated. At the same time, the desired braking deceleration is calculated based on the brake pedal displacement, and the desired braking force is calculated based on the desired braking deceleration. The initial braking force is distributed to the vehicle based on the proportion of the vertical load of each wheel and the desired braking force.

[0017] Furthermore, the vertical load of each wheel is calculated as follows:

[0018]

[0019] in, , , , The vertical loads are for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. m For the overall vehicle weight; It is the acceleration due to gravity; b This is the distance from the vehicle's center of gravity to the rear axle. It is longitudinal acceleration; It is lateral acceleration; Wheelbase; The height of the center of mass; c Wheelbase; a This is the distance from the vehicle's center of gravity to the front axle.

[0020] Furthermore, the initial braking force of each wheel is calculated as follows:

[0021]

[0022] in, , , , The braking forces are respectively for the left front wheel, right front wheel, left rear wheel, and right rear wheel; F d For the expected braking force; , , , The vertical loads are for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0023] Furthermore, the desired yaw rate and desired sideslip angle of the vehicle are calculated as follows:

[0024]

[0025]

[0026] in, denoted as the vehicle's desired yaw rate; min is the function for finding the minimum value. The longitudinal speed of the vehicle; The steering angle of the front wheels; For factors related to vehicle stability; This refers to the wheelbase; The ground adhesion coefficient; It is the acceleration due to gravity; It is a symbolic function; The desired sideslip angle of the vehicle's center of gravity; m For the overall vehicle weight; a This is the distance from the vehicle's center of gravity to the front axle. k f For front axle lateral stiffness; L This refers to the wheelbase; b This is the distance from the vehicle's center of gravity to the rear axle. k r This refers to the rear axle lateral stiffness.

[0027] Furthermore, the calculation methods for the torque adjustment amounts of the yaw rate and the sideslip angle are as follows:

[0028]

[0029]

[0030] in, The torque adjustment amount for the yaw rate; Let be the moment of inertia of the vehicle about the z-axis; , For state feedback coefficients; , The coefficient of the exponential rate of convergence; s is the sign function; s is the sliding surface; t is the time variable; This is the torque adjustment amount for the sideslip angle of the center of mass; , is the coefficient of the exponential convergence rate; a is the distance from the vehicle's center of gravity to the front axle; b is the distance from the vehicle's center of gravity to the rear axle; For front axle lateral stiffness; is the rear axle lateral stiffness; m is the vehicle mass; This represents the vehicle's longitudinal speed.

[0031] Furthermore, an error weighting ratio method is used to dynamically adjust the torque adjustment amounts for yaw rate and sideslip angle to obtain the desired braking torque to be applied to the wheels, specifically:

[0032]

[0033]

[0034] in, The desired braking torque that needs to be applied to the wheels; These are the weighting coefficients; This is the torque adjustment amount for the sideslip angle of the center of mass; This is the torque adjustment amount for the yaw rate.

[0035] Furthermore, the calculation method for the slip ratio compensation torque of each wheel is as follows:

[0036]

[0037] in, Torque to compensate for the slip ratio of each wheel; This is the proportionality coefficient; This is the difference between the expected slip ratio and the average slip ratio. The integral coefficient; is the differential coefficient.

[0038] Furthermore, the secondary braking force distribution to each wheel of the vehicle, based on the desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel, includes:

[0039] The desired braking torque to be applied to the wheels is distributed to each wheel according to the proportional relationship of the vertical load on each wheel, specifically as follows:

[0040]

[0041] in, , , , These are the braking torque adjustment amounts for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0042] The braking torque of each wheel is corrected by adjusting the braking torque of each wheel, specifically as follows:

[0043]

[0044] in, , , , These are the corrected braking torques for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0045] The slip ratio compensation torque of each wheel is distributed to each wheel according to the proportional relationship of the vertical load of each wheel, specifically as follows:

[0046]

[0047] in, , , , These are the vertical loads of the left front wheel, right front wheel, left rear wheel, and right rear wheel after adjustment based on slip ratio control.

[0048] The desired braking force required for each wheel is calculated based on the vertical load on each wheel, specifically as follows:

[0049]

[0050] in, , , , The desired braking force for the corrected left front wheel, right front wheel, left rear wheel, and right rear wheel; c This refers to the wheel track.

[0051] Secondly, the present invention proposes a vehicle cornering braking force distribution control system equipped with an electromechanical braking system that applies the above-mentioned method, comprising:

[0052] The state parameter sensing unit is used to obtain the real-time state information of the vehicle in response to the vehicle's turning and braking requirements.

[0053] The yaw-side slip coordinated control unit is used to calculate the vehicle's desired yaw rate and desired center-of-gravity sideslip angle using a linear two-degree-of-freedom vehicle steady-state model based on the vehicle's longitudinal speed and steering wheel angle. Based on the desired yaw rate, desired center-of-gravity sideslip angle, and actual yaw rate and actual center-of-gravity sideslip angle, a torque adjustment controller calculates the torque adjustment amounts for the yaw rate and center-of-gravity sideslip angle. An error weighting proportional allocation method is used to dynamically adjust the torque adjustment amounts for the yaw rate and center-of-gravity sideslip angle to obtain the desired braking torque to be applied to the wheels. Based on the vehicle speed and wheel rotation speed, a compensation torque controller calculates the slip ratio compensation torque for each wheel.

[0054] The braking force distribution control unit is used to initially distribute the braking force to the vehicle based on the vehicle's longitudinal acceleration; and to distribute the braking force to each wheel of the vehicle in a secondary manner based on the desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel.

[0055] The present invention has the following beneficial effects:

[0056] (1) This invention proposes an improved additional yaw moment estimation algorithm for the control strategy of vehicles equipped with electromechanical braking systems in cornering. By distributing the braking force in layers, the initial distribution is adapted to the static load characteristics. The dynamic correction layer is combined with the yaw-side slip control module and slip ratio feedback, which improves the wheel speed synchronization, avoids the risk of single-sided wheel lock-up, and enables the vehicle to ensure stability in complex steering and braking scenarios, thereby enhancing the vehicle's handling performance.

[0057] (2) The present invention uses an error weight ratio allocation method to adjust the braking torque of the yaw rate and the center of gravity side slip angle control output, thereby improving the accuracy of the braking force distribution system.

[0058] (3) In view of the problems of easy oscillation in response delay of vehicle brake-by-wire and the decline in reference output adjustment performance, the present invention designs a wheel slip ratio feedback controller to compensate for the distribution of braking force, thereby improving braking efficiency and control accuracy. Attached Figure Description

[0059] Figure 1 This is a flowchart illustrating an embodiment of the present invention;

[0060] Figure 2 This is a flowchart illustrating another embodiment of the present invention;

[0061] Figure 3 This is a schematic diagram of the system structure of the present invention;

[0062] Figure 4 This is a schematic diagram of the system principle of the present invention. Detailed Implementation

[0063] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0064] like Figure 1 As shown, an embodiment of the present invention provides a method for controlling the distribution of braking force during vehicle cornering equipped with an electromechanical braking system, comprising the following steps S101 to S107:

[0065] S101. In response to the vehicle's turning and braking demand information, obtain the vehicle's real-time status information;

[0066] In this embodiment, when a turning braking demand is detected, the real-time status information of the vehicle is obtained, including vehicle dynamics status signals, steering wheel angle signals, and yaw rate signals collected by the wheel-integrated sensing module; wheel speed and tire pressure collected by the sensors installed on each wheel; and vehicle dynamics status signals, steering wheel angle signals, and yaw rate signals collected by the vehicle body status sensing module.

[0067] S102. Distribute initial braking force to the vehicle based on its longitudinal acceleration;

[0068] In this embodiment, after the vehicle needs to turn and brake and real-time information of the vehicle is obtained, the vertical load of each wheel is calculated based on the longitudinal lateral acceleration, and the proportion of the vertical load of each wheel is calculated; at the same time, the desired braking deceleration is calculated based on the brake pedal displacement, and the desired braking force is calculated based on the desired braking deceleration; the initial braking force is distributed to the vehicle based on the proportion of the vertical load of each wheel and the desired braking force.

[0069] This embodiment establishes a vehicle cornering braking load transfer model based on the vehicle's state parameters. When a cornering demand is detected, real-time signals are acquired (sampling frequency 100Hz), and after data preprocessing, the longitudinal acceleration is output. Lateral acceleration Actual yaw rate Actual centroid sideslip angle Rotation speed of each wheel , , , and steering wheel angle The critical states are estimated by establishing a vehicle cornering braking load transfer model.

[0070] Vertical load estimation (taking left turn motion as an example):

[0071]

[0072] in, , , , The vertical loads are for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. m For the overall vehicle weight; It is the acceleration due to gravity; b This is the distance from the vehicle's center of gravity to the rear axle. It is longitudinal acceleration; It is lateral acceleration; This refers to the wheelbase; The height of the center of mass; c Wheelbase; a This is the distance from the vehicle's center of gravity to the front axle.

[0073] The formula for calculating the desired braking force is:

[0074]

[0075] in, The desired braking deceleration; For the desired braking force.

[0076] The initial braking force of each wheel is calculated as follows:

[0077]

[0078] in, , , , The braking forces are respectively for the left front wheel, right front wheel, left rear wheel, and right rear wheel; F d For the expected braking force; , , , The vertical loads are for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0079] S103. Based on the vehicle's longitudinal velocity and steering wheel angle, use a linear two-degree-of-freedom vehicle steady-state model to calculate the vehicle's desired yaw rate and desired center-of-gravity sideslip angle.

[0080] In this embodiment, after the initial distribution of vehicle braking force is completed, the acquired longitudinal vehicle speed and steering wheel angle are input into the linear two-degree-of-freedom vehicle steady-state model to obtain the vehicle's desired yaw rate and desired center of mass deviation angle.

[0081] Considering the steering angle The differential equations for the net external force along the y-axis and the net moment about the center of mass of the linear two-degree-of-freedom car model are very small:

[0082]

[0083] Bundle Substituting into the above equation, it can be transformed into:

[0084]

[0085] In the formula, The yaw rate is angular velocity (rad / s). The centroid sideslip angle (rad); The front axle lateral stiffness (N / rad); Rear axle lateral stiffness (N / rad); The longitudinal speed of the vehicle; This represents the vehicle's lateral speed.

[0086] This embodiment obtains the desired yaw rate and desired centroid sideslip angle by acquiring the actual yaw rate and centroid sideslip angle through a linear two-degree-of-freedom steady-state model:

[0087]

[0088]

[0089] in, denoted as the vehicle's desired yaw rate; min is the function for finding the minimum value. The longitudinal speed of the vehicle; for; For factors related to vehicle stability, ; This refers to the wheelbase; The ground adhesion coefficient; It is the acceleration due to gravity; It is a symbolic function; The desired sideslip angle of the vehicle's center of gravity; m For the overall vehicle weight; a This is the distance from the vehicle's center of gravity to the front axle. k f For front axle lateral stiffness; L This refers to the wheelbase; b This is the distance from the vehicle's center of gravity to the rear axle. kr This refers to the rear axle lateral stiffness.

[0090] S104. Based on the vehicle's desired yaw rate and desired sideslip angle, as well as the actual yaw rate and actual sideslip angle, a torque adjustment controller is used to calculate the torque adjustment amount for the yaw rate and the torque adjustment amount for the sideslip angle.

[0091] In this embodiment, after calculating the desired yaw rate and desired sideslip angle of the current vehicle, the desired yaw rate is compared with the actual yaw rate, and the desired sideslip angle is compared with the actual sideslip angle. The difference obtained from the comparison is input into the yaw rate control module and the sideslip angle control module, respectively, to adjust the dynamic performance of the vehicle.

[0092] This embodiment employs a sliding mode control algorithm, using the deviation between the calculated expected value and the collected actual value as input to establish a sliding mode controller: based on the deviation of the yaw rate... As input, design a sliding mode controller to generate the yaw torque adjustment:

[0093]

[0094] Define the sliding surface:

[0095]

[0096] in, It is the relative weight of the yaw rate deviation, and it is greater than 0.

[0097] From the two-degree-of-freedom differential equation, we get:

[0098]

[0099] Choose the exponential rate of convergence, i.e.:

[0100]

[0101] in, , The coefficient representing the exponential rate of convergence; to ensure the system can converge quickly and chattering is reduced, it should be increased. And reduce synchronously .

[0102] The torque adjustment amount for obtaining the yaw rate is:

[0103]

[0104] The deviation of the centroid sideslip angle As input, design a sliding mode controller to generate the yaw torque adjustment:

[0105]

[0106] Define the sliding surface:

[0107]

[0108] in, It is the relative weight of the centroid sideslip angle deviation, and it is greater than 0.

[0109] From the two-degree-of-freedom differential equation, we get:

[0110]

[0111] Similarly, the exponential rate of convergence is used, i.e.:

[0112]

[0113] in, , The coefficient representing the exponential rate of convergence; to ensure the system can converge quickly and chattering is reduced, it should be increased. And reduce synchronously .

[0114] The torque adjustment amount for obtaining the centroid sideslip angle is:

[0115]

[0116] S105. The torque adjustment amount of yaw rate and the torque adjustment amount of center of gravity sideslip angle are dynamically adjusted by using the error weight ratio allocation method to obtain the desired braking torque that needs to be applied to the wheel.

[0117] In this embodiment, since there is a coupling relationship between the vehicle's actual yaw rate and center of gravity deviation angle, the desired braking torque to be applied to the wheels is obtained by dynamically adjusting the error weight ratio allocation method.

[0118] In this embodiment, the braking torque adjustment amounts for yaw rate control and center-of-gravity sideslip angle control are adjusted using an error weighting ratio method. This is because the stability of cornering braking is affected by both factors, and the weighting coefficients are adjusted accordingly. Defined as:

[0119]

[0120] The desired braking torque that needs to be applied to the wheels is:

[0121]

[0122] in, The desired braking torque that needs to be applied to the wheels; These are the weighting coefficients; This is the torque adjustment amount for the sideslip angle of the center of mass; This is the torque adjustment amount for the yaw rate.

[0123] S106. Based on the vehicle speed and wheel rotation speed, a compensation torque controller is used to calculate the slip ratio compensation torque of each wheel.

[0124] In this embodiment, after calculating the adjustment amount of the yaw moment, the secondary distribution amount of braking force of each wheel in the vehicle is calculated based on the difference between the expected slip ratio and the average slip ratio calculated from the vehicle speed and wheel speed.

[0125] This embodiment employs a PID control algorithm to establish a PID slip ratio controller to obtain the desired braking torque for each wheel. Using the PID control method, the slip ratio of each wheel is detected in real time, fully utilizing the relationship between the ground surface and the slip ratio to adjust the braking force distribution to each wheel. The single-wheel slip ratio is defined as:

[0126]

[0127] In the formula, This refers to the rotational speed of the left front wheel. This refers to the rotational speed of the right front wheel; The speed of the left rear wheel; The speed of the right rear wheel; The radius of the wheel; For the left front wheel slip ratio, Right front wheel slip ratio Left rear wheel slip ratio Right rear wheel slip ratio; The vehicle speed.

[0128] The horizontal weighted average slip ratio is:

[0129]

[0130] by Design a PID controller for the input:

[0131]

[0132] in, Torque to compensate for the slip ratio of each wheel; This is the proportionality coefficient; This is the difference between the expected slip ratio and the average slip ratio. The integral coefficient; is the differential coefficient.

[0133] S107. Distribute the braking force to each wheel of the vehicle in a secondary manner, based on the desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel.

[0134] In this embodiment, the braking torque of the four wheels is adjusted twice to meet the required additional yaw torque. Specifically, increasing the braking force on the left wheel and decreasing the braking force on the right wheel generates a positive additional yaw torque; conversely, decreasing the braking force on the left wheel and increasing the braking force on the right wheel generates a negative additional yaw torque.

[0135] Taking the left turn as an example, for the braking torque adjustment amount controlled by yaw rate and the braking torque adjustment amount controlled by center of gravity sideslip angle, the following will be implemented: The vertical load is distributed to the four wheels according to the proportional relationship of each wheel's vertical load:

[0136] Specifically:

[0137]

[0138] in, , , , These are the braking torque adjustment amounts for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0139] The braking torque of each wheel is corrected by adjusting the braking torque of each wheel, specifically as follows:

[0140]

[0141] in, , , , These are the corrected braking torques for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0142] Taking a left turn as an example, for the slip ratio PID controller, the slip ratio compensation torque of each wheel is distributed to the four wheels according to the proportional relationship of the vertical load of each wheel, specifically as follows:

[0143]

[0144] in, , , , These are the vertical loads of the left front wheel, right front wheel, left rear wheel, and right rear wheel after adjustment based on slip ratio control.

[0145] The desired braking force required for each wheel is calculated based on the vertical load on each wheel, specifically as follows:

[0146]

[0147] in, , , , The desired braking force for the corrected left front wheel, right front wheel, left rear wheel, and right rear wheel; c This refers to the wheel track.

[0148] After completing the secondary distribution of braking force, the braking force distribution control to each wheel will be terminated when the braking demand is detected.

[0149] In some embodiments, such as Figure 2 As shown, the complete implementation process of the vehicle turning braking force distribution method provided in this application includes, but is not limited to, the following steps:

[0150] S210. After detecting a turning braking requirement, obtain the vehicle's real-time status information.

[0151] S220. Distribute the initial braking force according to the desired braking force and the vertical load ratio of each wheel.

[0152] S230. Compare the desired yaw rate and desired centroid sideslip angle calculated by the linear two-degree-of-freedom model with the actual yaw rate and actual centroid sideslip angle in the real-time state information to obtain the required yaw torque adjustment amount.

[0153] S240. The slip ratio of each wheel obtained by the slip ratio calculation model is compared with the average slip ratio to obtain the required compensation torque;

[0154] S250. Determine whether the yaw torque adjustment is greater than or equal to 0. If yes, proceed to step S260; otherwise, proceed to step S270.

[0155] S260: The initial braking force value of each inner wheel plus the secondary distribution braking force value; the initial braking force value of each outer wheel minus the secondary distribution braking force value.

[0156] S270: The initial braking force value of each inner wheel is reduced by the secondary distribution braking force value; the initial braking force value of each outer wheel is increased by the secondary distribution braking force value.

[0157] S280. Determine whether the braking demand needs to be released. If not, proceed to step S220; otherwise, end the braking force distribution process.

[0158] like Figure 3 As shown, this embodiment of the invention provides a vehicle cornering braking force distribution control system equipped with an electromechanical braking system that applies the above-described method, comprising:

[0159] The state parameter sensing unit is used to obtain the real-time state information of the vehicle in response to the vehicle's turning and braking requirements.

[0160] The yaw-side slip coordinated control unit is used to calculate the vehicle's desired yaw rate and desired center-of-gravity sideslip angle using a linear two-degree-of-freedom vehicle steady-state model based on the vehicle's longitudinal speed and steering wheel angle. Based on the desired yaw rate, desired center-of-gravity sideslip angle, and actual yaw rate and actual center-of-gravity sideslip angle, a torque adjustment controller calculates the torque adjustment amounts for the yaw rate and center-of-gravity sideslip angle. An error weighting proportional allocation method is used to dynamically adjust the torque adjustment amounts for the yaw rate and center-of-gravity sideslip angle to obtain the desired braking torque to be applied to the wheels. Based on the vehicle speed and wheel rotation speed, a compensation torque controller calculates the slip ratio compensation torque for each wheel.

[0161] The braking force distribution control unit is used to initially distribute the braking force to the vehicle based on the vehicle's longitudinal acceleration; and to distribute the braking force to each wheel of the vehicle in a secondary manner based on the desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel.

[0162] In this embodiment, the state parameter sensing unit is used to collect various data related to the vehicle's state during vehicle operation, providing the necessary key information for the yaw control unit, braking force control unit, and tire slip ratio control unit; the unit includes: an on-wheel integrated sensing module, a vehicle body state sensing module, and a state parameter estimation module;

[0163] Wheel-integrated sensor modules are installed on each wheel to collect wheel speed and tire pressure.

[0164] The vehicle body state sensing module collects vehicle dynamics state signals and steering wheel angle signals;

[0165] The state parameter estimation module is used to filter the various state data collected by the above-mentioned sensing modules, estimate the relevant state quantities, and package them to send to the yaw-side slip coordination control unit, the vehicle slip rate feedback adjustment unit, and the braking force hierarchical distribution control unit.

[0166] In this embodiment, the yaw-side slip coordinated control unit is used to obtain the desired yaw torque required to achieve vehicle stability and the desired braking torque required to prevent wheel slippage, and sends them to the braking force hierarchical distribution control unit. It includes: a yaw rate tracking module, a center of gravity side slip angle tracking module, and a slip ratio tracking module;

[0167] The yaw rate tracking module is used to calculate the desired yaw rate based on the state data provided by the state sensing unit. Through tracking control, it obtains the desired yaw torque required to track the actual yaw rate of the vehicle and ensures the stability of the vehicle during normal driving.

[0168] The center of gravity sideslip angle tracking module is used to calculate the desired center of gravity sideslip angle based on the state data provided by the state sensing unit. Through tracking control, the desired yaw moment required to track the actual center of gravity sideslip angle of the vehicle is obtained, ensuring the stability of the vehicle during normal driving.

[0169] The slip ratio tracking module is used to calculate the desired slip ratio based on the state data provided by the state sensing unit. Through tracking control, it obtains the desired braking torque of each wheel required to track the desired slip ratio, thereby avoiding wheel slippage during vehicle braking.

[0170] In this embodiment, the braking force layered distribution control unit is used to solve the braking force control problem while meeting the requirements of yaw moment control and tire slip ratio control, and to solve the stability problem of the vehicle's cornering braking system. It includes: an initial braking force distribution layer and a dynamic braking force correction layer;

[0171] The initial braking force distribution layer is used to initially distribute braking force based on the principle that when the braking intensity equals the coefficient of adhesion of each wheel, the braking force distribution will achieve ideal braking force distribution, thereby improving the braking efficiency of the vehicle.

[0172] The braking force dynamic correction layer is used to coordinate the braking force distribution among the wheels based on the expected yaw moment obtained by the yaw rate and center of gravity sideslip angle tracking module and the expected braking torque of each wheel obtained by the slip ratio tracking module, and to calculate the expected braking force of each wheel.

[0173] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0174] 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.

[0175] 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.

[0176] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0177] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for controlling the distribution of braking force during cornering in a vehicle equipped with an electromechanical braking system, characterized in that, Includes the following steps: In response to vehicle turning and braking requirements, obtain real-time vehicle status information; The initial braking force is distributed to the vehicle based on its longitudinal acceleration. Based on the vehicle's longitudinal velocity and steering wheel angle, a linear two-degree-of-freedom vehicle steady-state model is used to calculate the vehicle's desired yaw rate and desired center-of-gravity sideslip angle. Based on the vehicle's desired yaw rate and desired sideslip angle, as well as the actual yaw rate and actual sideslip angle, a torque adjustment controller is used to calculate the torque adjustment amount for the yaw rate and the torque adjustment amount for the sideslip angle. The torque adjustment of yaw rate and the torque adjustment of center of gravity sideslip angle are dynamically adjusted by using the error weight ratio allocation method to obtain the desired braking torque required on the wheel. Based on the vehicle speed and wheel rotation speed, a compensation torque controller is used to calculate the slip ratio compensation torque for each wheel; The desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel are used to perform secondary braking force distribution to each wheel of the vehicle. The calculation methods for the torque adjustment amounts of yaw rate and center of mass sideslip angle are as follows: in, The torque adjustment amount for the yaw rate; Let be the moment of inertia of the vehicle about the z-axis; , For state feedback coefficients; , The coefficient of the exponential rate of convergence; s is the sign function; s is the sliding surface; t is the time variable; This is the torque adjustment amount for the sideslip angle of the center of mass; , The coefficient of the exponential rate of convergence; For front axle lateral stiffness; is the rear axle lateral stiffness; m is the vehicle mass; The longitudinal speed of the vehicle; The torque adjustment amounts for yaw rate and sideslip angle are dynamically adjusted using an error weighting ratio method to obtain the desired braking torque to be applied to the wheels, specifically: in, The desired braking torque that needs to be applied to the wheels; These are the weighting coefficients; This is the torque adjustment amount for the sideslip angle of the center of mass; The torque adjustment amount for the yaw rate; The calculation method for the slip ratio compensation torque of each wheel is as follows: in, Torque to compensate for the slip ratio of each wheel; This is the proportionality coefficient; This is the difference between the expected slip ratio and the average slip ratio. The integral coefficient; These are the differential coefficients; The secondary braking force distribution to each wheel of the vehicle, based on the desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel, includes: The desired braking torque to be applied to the wheels is distributed to each wheel according to the proportional relationship of the vertical load on each wheel, specifically as follows: in, , , , These are the required braking torque adjustments for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. The braking torque of each wheel is corrected by adjusting the braking torque of each wheel, specifically as follows: in, , , , These are the corrected braking torques for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. The slip ratio compensation torque of each wheel is distributed to each wheel according to the proportional relationship of the vertical load of each wheel, specifically as follows: in, , , , These are the vertical loads of the left front wheel, right front wheel, left rear wheel, and right rear wheel after adjustment based on slip ratio control. The desired braking force required for each wheel is calculated based on the vertical load on each wheel, specifically as follows: in, , , , The desired braking force for the corrected left front wheel, right front wheel, left rear wheel, and right rear wheel; c This refers to the wheel track.

2. The method for controlling the distribution of braking force during vehicle turning, equipped with an electromechanical braking system, as described in claim 1, is characterized in that... The initial braking force distribution to the vehicle based on its longitudinal acceleration includes: The vertical load of each wheel is calculated based on the longitudinal lateral acceleration, and the proportion of the vertical load of each wheel is calculated. At the same time, the desired braking deceleration is calculated based on the brake pedal displacement, and the desired braking force is calculated based on the desired braking deceleration. The initial braking force is distributed to the vehicle based on the proportion of the vertical load of each wheel and the desired braking force.

3. The method for controlling the distribution of braking force during vehicle turning, equipped with an electromechanical braking system, as described in claim 2, is characterized in that... The vertical load of each wheel is calculated as follows: in, , , , The vertical loads are for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. m For the overall vehicle weight; It is the acceleration due to gravity; a This is the distance from the vehicle's center of gravity to the front axle; b This is the distance from the vehicle's center of gravity to the rear axle; It is longitudinal acceleration; It is lateral acceleration; This refers to the wheelbase; The height of the center of mass; c This refers to the wheel track.

4. A method for controlling the distribution of braking force during vehicle cornering, based on claim 1 or 2, characterized in that, The initial braking force of each wheel is calculated as follows: in, , , , The braking forces are respectively for the left front wheel, right front wheel, left rear wheel, and right rear wheel; F d For the expected braking force; , , , The vertical loads are for the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

5. A method for controlling the distribution of braking force during vehicle turning, equipped with an electromechanical braking system, as described in claim 3, is characterized in that... The desired yaw rate and desired sideslip angle of the vehicle are calculated as follows: in, denoted as the vehicle's desired yaw rate; min is the function for finding the minimum value. The longitudinal speed of the vehicle; The steering angle of the front wheels; For factors related to vehicle stability; This refers to the wheelbase; The ground adhesion coefficient; It is the acceleration due to gravity; It is a symbolic function; The desired sideslip angle of the vehicle's center of gravity; m For the overall vehicle weight; k f For front axle lateral stiffness; L This refers to the wheelbase; k r This refers to the rear axle lateral stiffness.

6. A vehicle cornering braking force distribution control system equipped with an electromechanical braking system applying the method of claim 1, characterized in that, include: The state parameter sensing unit is used to obtain the real-time state information of the vehicle in response to the vehicle's turning and braking requirements. The yaw-side slip coordinated control unit is used to calculate the vehicle's desired yaw rate and desired center-of-gravity sideslip angle using a linear two-degree-of-freedom vehicle steady-state model based on the vehicle's longitudinal speed and steering wheel angle. Based on the desired yaw rate, desired center-of-gravity sideslip angle, and actual yaw rate and actual center-of-gravity sideslip angle, a torque adjustment controller calculates the torque adjustment amounts for the yaw rate and center-of-gravity sideslip angle. An error weighting proportional allocation method is used to dynamically adjust the torque adjustment amounts for the yaw rate and center-of-gravity sideslip angle to obtain the desired braking torque to be applied to the wheels. Based on the vehicle speed and wheel rotation speed, a compensation torque controller calculates the slip ratio compensation torque for each wheel. The braking force distribution control unit is used to initially distribute the braking force to the vehicle based on the vehicle's longitudinal acceleration; and to distribute the braking force to each wheel of the vehicle in a secondary manner based on the desired braking torque applied to the wheels and the slip ratio compensation torque of each wheel.

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