Vehicle brake force distribution method, device and on-board controller

Abstract

The application provides a vehicle braking force distribution method, device and vehicle-mounted controller, and comprises the following steps: obtaining a desired braking force, a maximum ground adhesion force of a vehicle, a maximum braking force that can be provided by a motor and a maximum braking force that can be recycled by a battery; selecting one of the desired braking force, the maximum ground adhesion force of the vehicle, the maximum braking force that can be provided by the motor and the maximum braking force that can be recycled by the battery as a first braking force, which satisfies a preset lower limit condition, and the first braking force is used to control wheel braking by an electric braking system; and determining front wheel braking force and rear wheel braking force of the electric braking according to the first braking force and a ground adhesion coefficient.

Description

Technical Field

[0001] This application relates to the field of control, and more specifically, to a method, apparatus and on-board controller for distributing braking force to a vehicle. Background Technology

[0002] With the continuous development of integrated and lightweight braking systems, as well as the electrification and intelligence of automobiles, brake-by-wire systems will inevitably become the mainstream choice for automotive braking systems in the future, and the safety performance of brake-by-wire systems is of paramount importance.

[0003] During online braking, if the front wheels brake before the rear wheels, the wheels will lock up. If the rear wheels lock up before the front wheels, the rear wheels will skid, posing a great threat to the safety of the driver and passengers.

[0004] Therefore, there is an urgent need for a method to distribute braking force between the front and rear wheels of a vehicle in order to ensure balanced braking between the front and rear wheels. Summary of the Invention

[0005] In view of this, this application provides a vehicle braking force distribution method, device, and on-board controller, as follows:

[0006] A method for distributing braking force to a vehicle, comprising:

[0007] To obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate;

[0008] The first braking force is selected from the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate, and the first braking force is used to enable the electric braking system to control the wheel braking.

[0009] Based on the first braking force and the ground adhesion coefficient, the front wheel braking force and the rear wheel braking force of the electric brake are determined.

[0010] The above methods may also include:

[0011] A second braking force is determined based on the desired braking force and the first braking force, the second braking force being used to enable the hydraulic brake system to control wheel braking.

[0012] Optionally, in the above method, determining the second braking force based on the desired braking force and the first braking force includes:

[0013] Determine the difference between the desired braking force and the first braking force;

[0014] Since the braking force difference is a positive number, the braking force difference is used as the second braking force.

[0015] Optionally, in the above method, determining the front and rear wheel braking forces based on the first braking force and the ground adhesion coefficient includes:

[0016] With 0 as the lower limit and the first braking force as the upper limit, a braking force set is set according to a preset step size. The braking force set includes at least two target braking forces arranged in ascending order.

[0017] Select one of the braking forces from the set of braking forces in ascending order as the first target braking force;

[0018] Based on the first target braking force and the preset front and rear braking force distribution curve, the first initial braking force and the second initial braking force corresponding to the first target braking force are determined. The preset front and rear braking force distribution curve is related to the ground adhesion coefficient.

[0019] The second target braking force is determined based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold.

[0020] The second target braking force is used as the rear wheel braking force, and the first target braking force corresponding to the second target braking force is used as the front wheel braking force.

[0021] Optionally, in the above method, determining the first initial braking force and the second initial braking force based on the first target braking force and the preset front and rear braking force distribution curve includes:

[0022] Obtain the first curve formula and the second curve formula corresponding to the preset front and rear braking force distribution curve. The first curve formula represents the relationship between the front wheel braking force, the rear wheel braking force and the ground adhesion coefficient and the vehicle mass. The second curve formula represents the relationship between the front wheel braking force and the rear wheel braking force and the ground adhesion coefficient and the vehicle size.

[0023] Based on the first target braking force and the first curve formula, the first initial braking force is obtained;

[0024] Based on the first target braking force and the second curve formula, the second initial braking force is obtained.

[0025] Optionally, in the above method, determining the second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold includes:

[0026] Determine whether the difference is less than the preset difference threshold to obtain a first determination result;

[0027] If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is not less than a preset difference threshold, then the braking force set is selected as the new first target braking force, which is greater than and adjacent to the first target braking force. Then, the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force is executed based on the first target braking force and the preset front and rear braking force distribution curve.

[0028] If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is less than a preset difference threshold, the first initial braking force and the second initial braking force are recorded, and the preset difference threshold is updated based on the difference.

[0029] Determine whether the first target braking force is the same as the first braking force, and obtain a second determination result;

[0030] If the second judgment result indicates that the first target braking force is different from the first braking force, select the one that is greater than and adjacent to the first target braking force in the braking force set as the new first target braking force, and perform the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve;

[0031] If the second judgment result indicates that the first target braking force is the same as the first braking force, the average of the recorded first initial braking force and the second initial braking force is taken to obtain the second target braking force.

[0032] Optionally, the method described above includes obtaining the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can recover, comprising:

[0033] Receive the brake pedal opening; based on the correspondence between the pedal opening and the braking force, determine the desired braking force corresponding to the brake pedal opening;

[0034] Obtain the vehicle mass and road surface adhesion coefficient; determine the vehicle weight based on the vehicle mass; obtain the vehicle's maximum ground adhesion force based on the vehicle weight and the road surface adhesion coefficient;

[0035] Obtain the motor speed, final drive ratio, and tire radius; determine the maximum braking force the motor can provide based on the motor speed; determine the maximum braking force the motor can provide based on the maximum braking force the motor can provide and the final drive ratio and tire radius;

[0036] Obtain the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius; based on the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius, determine the maximum regenerative braking force of the battery.

[0037] A vehicle brake force distribution device, comprising:

[0038] The module is used to obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate.

[0039] The selection module is used to select one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as the first braking force, which meets a preset lower limit condition. The first braking force is used to enable the electric braking system to control the wheel braking.

[0040] The determination module is used to determine the front wheel braking force and the rear wheel braking force of the electric braking system based on the first braking force and the ground adhesion coefficient.

[0041] Optionally, in the above method, the determining module includes:

[0042] The setting unit is used to set a braking force set with 0 as the lower limit and the first braking force as the upper limit, according to a preset step size. The braking force set includes at least two target braking forces arranged in ascending order.

[0043] The selection unit is used to select one of the braking forces in the set of braking forces in ascending order as the first target braking force.

[0044] The first determining unit is used to determine the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve, wherein the preset front and rear braking force distribution curve is related to the ground adhesion coefficient.

[0045] The second determining unit is used to determine the second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold.

[0046] The third determining unit is used to use the second target braking force as the rear wheel braking force and the first target braking force corresponding to the second target braking force as the front wheel braking force.

[0047] An on-board controller, characterized in that it comprises: a memory and a processor;

[0048] The memory stores the processing program;

[0049] Each step of the vehicle braking force distribution method described in any of the above items.

[0050] In summary, this application provides a vehicle braking force distribution method, device, and on-board controller, comprising: obtaining a desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate; selecting one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as a first braking force that meets a preset lower limit condition, the first braking force being used to enable the electric braking system to control wheel braking; and determining the electric braking force for the front wheels and the braking force for the rear wheels based on the first braking force and the ground adhesion coefficient. In this embodiment, the first braking force for the electric braking system to control wheel braking is first determined, and the first braking force is distributed according to the ground adhesion coefficient to ensure that the front wheel braking force and the rear wheel braking force are balanced, ensuring that the braking of the front and rear wheels is controlled separately based on the front wheel braking force and the rear wheel braking force, thus ensuring balanced braking and preventing wheel lock-up or rear wheel sideslip. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0052] Figure 1 This is a flowchart of an embodiment 1 of a vehicle braking force distribution method provided in this application;

[0053] Figure 2 This is a schematic diagram of the braking force determination process in Embodiment 1 of a vehicle braking force distribution method provided in this application;

[0054] Figure 3 This is a flowchart of Embodiment 2 of a vehicle braking force distribution method provided in this application;

[0055] Figure 4 This is a schematic diagram of the braking force determination process in Embodiment 2 of the vehicle braking force distribution method provided in this application;

[0056] Figure 5 This is a flowchart of Embodiment 3 of a vehicle braking force distribution method provided in this application;

[0057] Figure 6 This is a schematic diagram of an embodiment of a vehicle brake force distribution device provided in this application. Detailed Implementation

[0058] 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, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0059] like Figure 1 The diagram shown is a flowchart of Embodiment 1 of a vehicle braking force distribution method provided in this application. The method is applied to an on-board controller for controlling a vehicle, and includes the following steps:

[0060] Step S101: Obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate.

[0061] In this application, the timing of obtaining the aforementioned desired braking force, maximum vehicle ground adhesion, maximum braking force provided by the motor, and maximum recyclable braking force by the battery is not limited; they can be obtained simultaneously or in any order.

[0062] It should be noted that the vehicle used in this application is specifically a four-wheel drive vehicle system, which is capable of braking the front and rear wheels separately.

[0063] Specifically, obtaining the desired braking force includes: receiving the brake pedal opening; and determining the desired braking force corresponding to the brake pedal opening based on the correspondence between the pedal opening and the braking force.

[0064] In this process, the driver presses the brake pedal during driving, and the desired braking force is determined based on the opening of the brake pedal.

[0065] Specifically, the vehicle controller has a preset correspondence between brake pedal opening and braking force, and determines the desired braking force corresponding to the current pedal opening based on this correspondence.

[0066] In practice, the correspondence can be a curve representing the correspondence, and the desired braking force corresponding to the current pedal opening can be found by looking up the curve. Alternatively, the correspondence can be a preset table, and the desired braking force corresponding to the current pedal opening can be found by looking up the table.

[0067] Specifically, obtaining the maximum ground adhesion of the vehicle includes: obtaining the vehicle mass and the road surface adhesion coefficient; determining the vehicle weight based on the vehicle mass; and obtaining the maximum ground adhesion of the vehicle based on the vehicle weight and the road surface adhesion coefficient.

[0068] The vehicle's weight is obtained by multiplying its mass and gravitational acceleration, and the maximum ground adhesion force is obtained by multiplying its weight and the road surface adhesion coefficient.

[0069] Specifically, obtaining the maximum braking force that the motor can provide includes: obtaining the motor speed, the final drive ratio, and the tire radius; determining the maximum braking force that the motor can provide based on the motor speed; and determining the maximum braking force that the motor can provide based on the maximum braking force that the motor can provide;

[0070] Specifically, the vehicle controller has a preset correspondence between motor speed and motor power, and determines the motor that provides braking force corresponding to the current motor speed based on this correspondence.

[0071] The braking force provided by the motor is multiplied by the main reduction ratio (also known as the rear axle speed ratio) to obtain the attenuated braking force provided by the motor. The attenuated braking force provided by the motor is divided by the tire radius to obtain the maximum braking force that the motor can provide.

[0072] Specifically, the maximum braking force that the motor can provide = motor power × main reduction ratio ÷ tire radius.

[0073] Specifically, obtaining the maximum recyclable braking force of the battery includes: obtaining the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius; and determining the maximum recyclable braking force of the battery based on the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius.

[0074] Among them, the upper limit of battery charging power is the maximum charging power of the battery, which is generally in the kW (kilowatt) level.

[0075] Specifically, the motor's power output is obtained by dividing the upper limit of the battery charging power by the motor's power generation efficiency. The motor's power output is then multiplied by the motor's actual speed to obtain the motor's power. The motor's power output is then multiplied by the main reduction ratio to obtain the attenuated motor's power output. Finally, the maximum regenerative braking force of the battery is obtained by dividing the attenuated motor's power output by the tire radius.

[0076] Specifically, the maximum recyclable braking force of the battery = upper limit of battery charging power ÷ motor power generation efficiency × actual motor speed × main reduction ratio ÷ tire radius.

[0077] It should be noted that, in specific implementation, the aforementioned expected braking force, maximum vehicle ground adhesion, maximum braking force provided by the motor, and maximum recyclable braking force of the battery can also be determined in other ways, and this application does not impose any restrictions on the determination method.

[0078] Step S102: Select one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as the first braking force, which satisfies a preset lower limit condition. The first braking force is used to enable the electric braking system to control the wheel braking.

[0079] It should be noted that, in order to fully utilize the ground adhesion coefficient and prevent slippage, the maximum braking force is limited by the maximum road surface adhesion. Therefore, the smaller of the desired braking force and the maximum ground adhesion is determined as the total required braking force. Secondly, in order to ensure the reliability of the motor and avoid battery overcharging, the braking force is limited by the maximum braking force that the motor can provide and the maximum charging power of the battery. Combining the above two objectives, the smallest of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum regenerative braking force of the battery needs to be determined as the first braking force.

[0080] like Figure 2 The diagram illustrates the braking force determination process. Input parameters include: brake pedal opening, vehicle weight, gravitational acceleration, road surface adhesion coefficient, motor speed, final drive ratio, tire radius, maximum battery charging power, motor power generation efficiency, and actual motor speed. The comparison unit uses MN, indicating that the minimum input value is used for output.

[0081] Specifically, the brake pedal opening is used to obtain the desired braking force based on the corresponding relationship curve 201. The vehicle weight is multiplied sequentially by the gravitational acceleration and the road surface adhesion coefficient to obtain the maximum ground adhesion. This desired braking force and the maximum ground adhesion are compared by a comparison unit, and the minimum value is output to obtain the total required braking force. The motor speed is used to obtain the braking force provided by the motor based on the corresponding relationship curve 202. This motor-provided braking force is multiplied by the final drive ratio and then divided by the tire radius to obtain the maximum braking force that the motor can provide. The maximum battery charging power is divided by the motor power generation efficiency, then multiplied sequentially by the motor speed and the final drive ratio, and then divided by the tire radius to obtain the maximum regenerative braking force of the battery. The total required braking force and the maximum braking force that the motor can provide are compared by a comparison unit, and the minimum value is output. This minimum value is then compared with the maximum regenerative braking force of the battery to obtain the maximum regenerative braking force.

[0082] Specifically, this first braking force can also be called the recyclable maximum braking force, which is the control braking force realized by the electric braking system.

[0083] Step S103: Determine the front wheel braking force and rear wheel braking force of the electric brake based on the first braking force and the ground adhesion coefficient.

[0084] The ground adhesion coefficient is the ratio of the adhesion force to the wheel's normal (perpendicular to the road surface) pressure. It can be considered as the static friction coefficient between the tire and the road surface.

[0085] Based on the determined first braking force and the ground adhesion coefficient, the front wheel braking force and the rear wheel braking force of the electric brake are determined to achieve the distribution of braking force between the front and rear wheels and the balance of braking force between the two.

[0086] In practice, the braking control of the front and rear wheels can be performed separately based on the determined braking forces of the front and rear wheels to ensure balanced braking and prevent wheel lock-up or rear wheel skidding.

[0087] It should be noted that the process of determining the front and rear braking forces of the electric braking system will be described in detail in subsequent embodiments, but will not be described in detail in this embodiment.

[0088] In summary, this embodiment provides a vehicle braking force distribution method, including: obtaining a desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate; selecting one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as a first braking force that meets a preset lower limit condition, the first braking force being used to enable the electric braking system to control wheel braking; and determining the electric braking force for the front and rear wheels based on the first braking force and the ground adhesion coefficient. In this embodiment, the first braking force for the electric braking system to control wheel braking is first determined, and the first braking force is distributed according to the ground adhesion coefficient to ensure that the front and rear wheel braking forces are balanced, ensuring that braking control of the front and rear wheels is performed separately based on the front and rear wheel braking forces, thus ensuring balanced braking and preventing wheel lock-up or rear wheel sideslip.

[0089] like Figure 3 The flowchart shown is a second embodiment of a vehicle braking force distribution method provided in this application. The method includes the following steps:

[0090] Step S301: Obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate.

[0091] Step S302: Select one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as the first braking force, which satisfies a preset lower limit condition. The first braking force is used to enable the electric braking system to control the wheel braking.

[0092] Step S303: Determine the front wheel braking force and rear wheel braking force of the electric brake based on the first braking force and the ground adhesion coefficient;

[0093] Steps S301-303 are consistent with the corresponding steps in Example 1, and will not be repeated in this example.

[0094] Step S304: Determine a second braking force based on the desired braking force and the first braking force, the second braking force being used to enable the hydraulic brake system to control wheel braking.

[0095] If the wheel control system uses both an electric braking system and a hydraulic braking system, after determining the first braking force of the electric braking system to control the wheel braking, it is also necessary to determine the second braking force of the hydraulic braking system to control the wheel braking.

[0096] Accordingly, in conjunction with the strategy of controlling wheel braking by the hydraulic braking system, the front wheel braking force and the rear wheel braking force are determined. The front wheel braking force and the rear wheel braking force determined by the hydraulic braking system, together with the electrically controlled front wheel braking force and the rear wheel braking force, jointly control the front wheel and rear wheel braking of the vehicle.

[0097] Specifically, step S304 includes:

[0098] Step S3041: Determine the braking force difference between the desired braking force and the first braking force;

[0099] Step S3042: Based on the fact that the braking force difference is a positive number, the braking force difference is used as the second braking force.

[0100] The desired braking force is subtracted from the first braking force to obtain the braking force difference, which is the requirement that exceeds the first braking force.

[0101] If the difference in braking force is positive, it indicates that the desired braking force cannot be met by the first braking force alone, and the hydraulic brake system needs to further supplement the difference.

[0102] like Figure 4 The diagram illustrates the braking force determination process. Input parameters include: brake pedal opening, vehicle weight, gravitational acceleration, road surface adhesion coefficient, motor speed, final drive ratio, tire radius, maximum battery charging power, motor power generation efficiency, and actual motor speed. Comparison unit MN indicates that the minimum input value is used for output, and comparison unit MX indicates that the maximum input value is used for output. For an explanation of the process of obtaining the first braking force, please refer to the explanation in Example 1; it will not be repeated in this example.

[0103] The desired braking force is obtained by subtracting the first braking force from the desired braking force, comparing the difference with 0, taking the maximum value, and summing the results to obtain the second braking force.

[0104] Specifically, this second braking force can also be called the hydraulic brake system's required braking force, which is specifically the control braking force implemented by the hydraulic brake system.

[0105] In summary, the vehicle braking force distribution method provided in this embodiment further includes: determining a second braking force based on the desired braking force and the first braking force, wherein the second braking force is used to enable the hydraulic braking system to control wheel braking. In this embodiment, the corresponding braking forces are determined for the electric braking system and the hydraulic braking system respectively, thereby realizing the braking force distribution between the two braking systems.

[0106] like Figure 5 The flowchart shown is a third embodiment of a vehicle braking force distribution method provided in this application. The method includes the following steps:

[0107] Step S501: Obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate.

[0108] Step S502: Select one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as the first braking force, which satisfies a preset lower limit condition. The first braking force is used to enable the electric braking system to control the wheel braking.

[0109] Steps S501-502 are consistent with the corresponding steps in Example 2, and will not be repeated in this example.

[0110] Step S503: Set the braking force set according to a preset step size, with 0 as the lower limit and the first braking force as the upper limit;

[0111] The braking force set includes at least two target braking forces arranged in ascending order.

[0112] It should be noted that, given the total braking force (first braking force) required from the front and rear wheels, in order to make full use of the ground adhesion and ensure that the front and rear wheels can lock up simultaneously, the total braking force needs to be reasonably distributed. In this embodiment, the distribution is carried out according to the front and rear braking force distribution curve.

[0113] First, the first braking force is set as the upper limit and 0 as the lower limit. Based on the preset step size, multiple target braking forces are determined. These multiple target braking forces are sorted from smallest to largest to obtain a set of braking forces.

[0114] The value of this step size is determined based on the torque change step size. The determination of this step size needs to consider both control accuracy and computing power. Specifically, it is necessary to ensure that the control accuracy and computing power are within acceptable limits.

[0115] For example, if the step size is selected as 100N (Newtons) and the first braking force is 1000N, the determined set of braking forces includes: 0, 100N, 200N, ..., 900N, 1000N.

[0116] Of course, the specific values ​​of the step size and the first braking force are not limited in this application. In actual implementation, the value of the step size can be set according to the actual situation.

[0117] Step S504: Select one of the braking forces from the set of braking forces in ascending order as the first target braking force;

[0118] Specifically, in this set of braking forces, one is selected as the first target braking force in ascending order, and the second target braking force corresponding to the first target braking force is determined.

[0119] For example, first select 0 as the first target braking force, and determine the second target braking force corresponding to 0; select 100N as the first target braking force, and determine the second target braking force corresponding to 100N, etc.

[0120] It should be noted that after selecting a primary target braking force, subsequent steps S505-506 are executed, and each step is executed cyclically.

[0121] Step S505: Based on the first target braking force and the preset front and rear braking force distribution curve, determine the first initial braking force and the second initial braking force corresponding to the first target braking force. The preset front and rear braking force distribution curve is related to the ground adhesion coefficient.

[0122] Specifically, the preset front and rear braking force distribution curve is an ideal front and rear braking force distribution curve, which can be expressed by a formula.

[0123] Specifically, the first initial braking force and the second initial braking force corresponding to the first target braking force are determined based on the preset front and rear braking force distribution curve.

[0124] The first initial braking force and the second initial braking force are used as intermediate values ​​to determine the second target braking force.

[0125] Specifically, step S505 includes:

[0126] Step S5051: Obtain the first curve formula and the second curve formula corresponding to the preset front and rear braking force distribution curves;

[0127] The first curve formula represents the relationship between the front wheel braking force, the rear wheel braking force, the ground adhesion coefficient, and the vehicle mass; the second curve formula represents the relationship between the front wheel braking force, the rear wheel braking force, the ground adhesion coefficient, and the vehicle size.

[0128] Specifically, the formula for the first curve is as follows:

[0129]

[0130] Among them, Fμ1 F represents the front wheel braking force. μ2 Indicates the braking force of the rear wheels. denoted by the ground adhesion coefficient, m represents the vehicle mass, and g represents the gravitational acceleration.

[0131] Specifically, the formula for the second curve is as follows:

[0132]

[0133] Among them, F μ1 F represents the front wheel braking force. μ2 Indicates the braking force of the rear wheels. The coefficient of friction is represented by 'a', where 'a' represents the distance from the vehicle's center of gravity to the front axle, 'b' represents the distance from the vehicle's center of gravity to the rear axle, and 'h' represents the coefficient of friction. g Indicates the height of the center of mass.

[0134] Step S5052: Obtain the first initial braking force based on the first target braking force and the first curve formula;

[0135] In this process, the first target braking force selected in step S504 is substituted into formula (1) as the front wheel braking force to obtain F. μ2 As the first initial braking force, it can be denoted as F. μ2-1 .

[0136] Step S5053: Based on the first target braking force and the second curve formula, obtain the second initial braking force.

[0137] Among them, the first target braking force selected in step S504 is substituted into formula (2) as the front wheel braking force to obtain F. μ2 As a second initial braking force.

[0138] Step S506: Determine the second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold.

[0139] The difference between the first initial braking force and the second initial braking force is calculated. This difference represents the gap between the braking forces used for rear wheel control determined by the two formulas. The larger the difference between the two, the larger the gap between them and the corresponding first target braking force. In order to ensure the balance between the front wheel braking force and the rear wheel braking force, it is necessary to ensure that the obtained first initial braking force is as close as possible to the second initial braking force and the first target braking force.

[0140] Specifically, step S506 includes:

[0141] Step S5061: Determine whether the difference is less than the preset difference threshold to obtain a first determination result;

[0142] Specifically, the difference between the first initial braking force and the second initial braking force is first calculated. This difference is an absolute value to determine the gap between the first initial braking force and the second initial braking force. Then, this difference is compared with a preset difference threshold.

[0143] Specifically, the first initial braking force determined in step S505 is denoted as F. μ2-1 The second initial braking force is denoted as F. μ2-2 The difference Δ = |F μ2-1 -F μ2-2 |

[0144] Specifically, it is determined whether the difference Δ is less than a preset difference threshold to obtain the first judgment result.

[0145] If the difference is not less than the preset difference threshold, step S5062 is executed; otherwise, step S5063 is executed.

[0146] Step S5062: If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is not less than a preset difference threshold, select the one that is greater than and adjacent to the first target braking force from the set of braking forces as the new first target braking force, and return to execute step S505.

[0147] If the difference is not less than the preset difference threshold, it indicates that the difference between the first initial braking force and the second initial braking force is large. The first target braking force is ignored, and the next first target braking force is selected to determine the corresponding first initial braking force and second initial braking force.

[0148] For example, if the first target braking force currently used is 500, the preset difference threshold is 1000, and the determined difference is 1500, it indicates that the difference between the first initial braking force and the second initial braking force is large. Therefore, the first target braking force and the corresponding first and second initial braking forces are not used to determine the second target braking force. According to the order from smallest to largest, the next target braking force is selected as 600. Then, the first target braking force is 600N, and the first and second initial braking forces corresponding to 600N are determined.

[0149] Step S5063: If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is less than a preset difference threshold, record the first initial braking force and the second initial braking force, and update the preset difference threshold according to the difference.

[0150] If the difference is less than a preset difference threshold, it indicates that the difference between the first initial braking force and the second initial braking force is small. The preset difference threshold can be updated with the difference so that the difference range can be further reduced when determining the difference between the first initial braking force and the second initial braking force in the future.

[0151] Furthermore, the first and second initial braking forces can be recorded to provide a calculation basis for subsequently determining the second target braking force.

[0152] It should be noted that if, after updating the preset difference threshold, a new first target force value is determined, and the difference between the new first initial braking force and the second initial braking force is less than the updated preset difference threshold, then the new first initial braking force and the second initial braking force are recorded, overwriting the original records.

[0153] Step S5064: Determine whether the first target braking force is the same as the first braking force, and obtain the second determination result;

[0154] Specifically, determining whether the first target braking force is the same as the first braking force is used to determine whether the first target braking force corresponding to the first initial braking force and the second braking force is the last one in the set of braking forces.

[0155] In this process, a target braking force is selected sequentially from the set of braking forces in ascending order as the first target braking force. If the selected first target braking force is the same as the first braking force, it indicates that the last target braking force in the set of braking forces has been selected, thus realizing the traversal of each target braking force in the set of braking forces. Otherwise, the last target braking force in the set of braking forces has not yet been selected, and the traversal of each target braking force in the set of braking forces has not been realized.

[0156] Step S5065: If the second judgment result indicates that the first target braking force is different from the first braking force, select the one that is greater than and adjacent to the first target braking force in the braking force set as the new first target braking force, and execute the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve.

[0157] If the currently selected first target braking force is different from the first braking force, it indicates that the last target braking force in the braking force set has not yet been selected. In this case, the target braking force that is adjacent to and larger than the first target braking force is selected as the new first target braking force, and the process returns to step S505 to obtain the new first initial braking force and the second initial braking force.

[0158] It should be noted that when returning to step S505, the difference between the new first initial braking force and the second initial braking force is judged according to the updated preset difference threshold.

[0159] It should be noted that the difference between the first initial braking force and the second initial braking force determined each time is compared with a preset difference threshold. If the difference is less than the preset difference threshold, the preset difference threshold is updated using the difference. If the difference is not less than the preset difference threshold, it is not updated, and the original difference threshold is used to continue the process of determining the first initial braking force and the second initial braking force for the next first target braking force. By updating the preset difference threshold based on a smaller difference, the preset difference threshold is gradually narrowed, so that the difference between the subsequently determined first initial braking force and the second initial braking force is within a small range.

[0160] The above process is repeated until the last target braking force in the braking force set is reached, which is the same as the first braking force.

[0161] Step S5066: If the second judgment result indicates that the first target braking force is the same as the first braking force, the average value of the recorded first initial braking force and the second initial braking force is taken to obtain the second target braking force.

[0162] If the first target braking force is the same as the first braking force, it indicates that the first target braking force is the last one in the braking force set, and the traversal of each target braking force in the braking force set is completed.

[0163] After traversing each target braking force in the braking force set, the first initial braking force and the second initial braking force recorded during the traversal are obtained. The first initial braking force and the second initial braking force recorded are the set with the smallest difference during the traversal, and are the closest to the first target braking force.

[0164] Specifically, the average of the recorded first and second initial braking forces is used to obtain the second target braking force.

[0165] Correspondingly, the second target braking force is also closest to the corresponding first target braking force, thus achieving a balanced distribution of the first braking force.

[0166] Step S507: Use the second target braking force as the rear wheel braking force, and use the first target braking force corresponding to the second target braking force as the front wheel braking force.

[0167] Specifically, the second target braking force is used as the rear wheel braking force, and the corresponding first target braking force is used as the front wheel braking force, thus achieving a balanced distribution of the first braking force to the front and rear wheel braking forces.

[0168] In summary, this embodiment provides a vehicle braking force distribution method, comprising: setting a braking force set according to a preset step size, with 0 as the lower limit and the first braking force as the upper limit; the braking force set including at least two target braking forces arranged in ascending order; selecting one of the braking forces in the braking force set in ascending order as the first target braking force; determining a first initial braking force and a second initial braking force corresponding to the first target braking force based on the first target braking force and a preset front-rear braking force distribution curve, wherein the preset front-rear braking force distribution curve is related to the ground adhesion coefficient; determining a second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold; using the second target braking force as the rear wheel braking force and the first target braking force corresponding to the second target braking force as the front wheel braking force. In this embodiment, by setting a braking force set as the first braking force, and determining the first initial braking force and the second initial braking force corresponding to the braking force set based on the preset front and rear braking force distribution curve related to the ground adhesion coefficient, the difference between the first initial braking force and the second initial braking force is compared with a preset difference threshold, and the preset difference threshold is updated so that the obtained first initial braking force and second initial braking force are close to the corresponding first target braking force, and finally the second target braking force is obtained. This ensures that the obtained second target braking force is close to the first target braking force. The second target braking force is used as the rear wheel braking force, and the first target braking force corresponding to the second target braking force is used as the front wheel braking force, thus realizing the balanced distribution of the first braking force to the front wheel braking force and the rear wheel braking force.

[0169] Corresponding to the above embodiment of the vehicle braking force distribution method provided in this application, this application also provides an embodiment of an apparatus for applying the vehicle braking force distribution method.

[0170] like Figure 6 The diagram shown is a structural schematic of an embodiment of a vehicle brake force distribution device provided in this application. The device includes the following structure: an acquisition module 601, a selection module 602, and a determination module 603.

[0171] The obtaining module 601 is used to obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can recycle.

[0172] The selection module 602 is used to select one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as the first braking force, which meets a preset lower limit condition. The first braking force is used to enable the electric braking system to control the wheel braking.

[0173] The determining module 603 is used to determine the front wheel braking force and the rear wheel braking force of the electric braking system based on the first braking force and the ground adhesion coefficient.

[0174] Optionally, the determining module includes:

[0175] The setting unit is used to set a braking force set with 0 as the lower limit and the first braking force as the upper limit, according to a preset step size. The braking force set includes at least two target braking forces arranged in ascending order.

[0176] The selection unit is used to select one of the braking forces in the set of braking forces in ascending order as the first target braking force.

[0177] The first determining unit is used to determine the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve, wherein the preset front and rear braking force distribution curve is related to the ground adhesion coefficient.

[0178] The second determining unit is used to determine the second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold.

[0179] The third determining unit is used to use the second target braking force as the rear wheel braking force and the first target braking force corresponding to the second target braking force as the front wheel braking force.

[0180] Optional, also includes:

[0181] The second braking force determination module is used to determine a second braking force based on the desired braking force and the first braking force, wherein the second braking force is used to enable the hydraulic brake system to control wheel braking.

[0182] Optional, a second braking force determination module, specifically used for:

[0183] Determine the difference between the desired braking force and the first braking force;

[0184] Since the braking force difference is a positive number, the braking force difference is used as the second braking force.

[0185] Optionally, the first determining unit is specifically used for:

[0186] Obtain the first curve formula and the second curve formula corresponding to the preset front and rear braking force distribution curve. The first curve formula represents the relationship between the front wheel braking force, the rear wheel braking force and the ground adhesion coefficient and the vehicle mass. The second curve formula represents the relationship between the front wheel braking force and the rear wheel braking force and the ground adhesion coefficient and the vehicle size.

[0187] Based on the first target braking force and the first curve formula, the first initial braking force is obtained;

[0188] Based on the first target braking force and the second curve formula, the second initial braking force is obtained.

[0189] Optionally, the second determining unit is specifically used for:

[0190] Determine whether the difference is less than the preset difference threshold to obtain a first determination result;

[0191] If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is not less than a preset difference threshold, then the braking force set is selected as the new first target braking force, which is greater than and adjacent to the first target braking force. Then, the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force is executed based on the first target braking force and the preset front and rear braking force distribution curve.

[0192] If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is less than a preset difference threshold, the first initial braking force and the second initial braking force are recorded, and the preset difference threshold is updated based on the difference.

[0193] Determine whether the first target braking force is the same as the first braking force, and obtain a second determination result;

[0194] If the second judgment result indicates that the first target braking force is different from the first braking force, select the one that is greater than and adjacent to the first target braking force in the braking force set as the new first target braking force, and perform the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve;

[0195] If the second judgment result indicates that the first target braking force is the same as the first braking force, the average of the recorded first initial braking force and the second initial braking force is taken to obtain the second target braking force.

[0196] Optional, obtain the module, specifically used for:

[0197] Receive the brake pedal opening; based on the correspondence between the pedal opening and the braking force, determine the desired braking force corresponding to the brake pedal opening;

[0198] Obtain the vehicle mass and road surface adhesion coefficient; determine the vehicle weight based on the vehicle mass; obtain the vehicle's maximum ground adhesion force based on the vehicle weight and the road surface adhesion coefficient;

[0199] Obtain the motor speed, final drive ratio, and tire radius; determine the maximum braking force the motor can provide based on the motor speed; determine the maximum braking force the motor can provide based on the maximum braking force the motor can provide and the final drive ratio and tire radius;

[0200] Obtain the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius; based on the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius, determine the maximum regenerative braking force of the battery.

[0201] It should be noted that the functional explanations of the various components in this embodiment of a vehicle braking force distribution device are provided in the explanations in the foregoing method embodiments, and will not be repeated in this embodiment.

[0202] In summary, this embodiment provides a vehicle braking force distribution device, comprising: an acquisition module for acquiring a desired braking force, the vehicle's maximum ground adhesion, the maximum braking force provided by the motor, and the maximum regenerative braking force of the battery; a selection module for selecting one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force provided by the motor, and the maximum regenerative braking force of the battery that meets a preset lower limit condition as a first braking force, the first braking force being used to enable the electric braking system to control wheel braking; and a determination module for determining the electric braking front wheel braking force and the rear wheel braking force based on the first braking force and the ground adhesion coefficient. In this embodiment, the first braking force for the electric braking system to control wheel braking is first determined, and then the first braking force is distributed according to the ground adhesion coefficient to ensure that the front wheel braking force and the rear wheel braking force are balanced, ensuring that the braking of the front and rear wheels is controlled separately based on the front wheel braking force and the rear wheel braking force, thus ensuring balanced braking and preventing wheel lock-up or rear wheel sideslip.

[0203] Corresponding to the above embodiment of the vehicle braking force distribution method provided in this application, this application also provides an on-board controller and a readable storage medium corresponding to the vehicle braking force distribution method.

[0204] The vehicle controller includes: a memory and a processor;

[0205] The memory stores the processing program;

[0206] The processor is used to load and execute the processing program stored in the memory to implement the steps of the vehicle braking force distribution method as described in any of the preceding claims.

[0207] For details on how the vehicle controller implements vehicle braking force distribution, please refer to the aforementioned vehicle braking force distribution method embodiment.

[0208] The readable storage medium stores a computer program that is invoked and executed by a processor to implement the steps of the vehicle braking force distribution method as described in any of the preceding claims.

[0209] Specifically, the computer program stored in the readable storage medium executes to implement the vehicle braking force distribution method, as can be found in the aforementioned vehicle braking force distribution method embodiments.

[0210] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The apparatus provided in the embodiments is described simply because it corresponds to the method provided in the embodiments; relevant parts can be found in the method section.

[0211] The above description of the provided embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features provided herein.

Claims

1. A method for distributing braking force to a vehicle, characterized in that, include: To obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate; The first braking force is selected from the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate, and the first braking force is used to enable the electric braking system to control the wheel braking. Based on the first braking force and the ground adhesion coefficient, determine the front wheel braking force and the rear wheel braking force of the electric brake; The determination of the front and rear wheel braking forces based on the first braking force and the ground adhesion coefficient includes: With 0 as the lower limit and the first braking force as the upper limit, a braking force set is set according to a preset step size. The braking force set includes at least two target braking forces arranged in ascending order. Select one of the braking forces from the set of braking forces in ascending order as the first target braking force; Based on the first target braking force and the preset front and rear braking force distribution curve, the first initial braking force and the second initial braking force corresponding to the first target braking force are determined. The preset front and rear braking force distribution curve is related to the ground adhesion coefficient. The second target braking force is determined based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold. The second target braking force is used as the rear wheel braking force, and the first target braking force corresponding to the second target braking force is used as the front wheel braking force.

2. The method according to claim 1, characterized in that, Also includes: A second braking force is determined based on the desired braking force and the first braking force, the second braking force being used to enable the hydraulic brake system to control wheel braking.

3. The method according to claim 2, characterized in that, Determining the second braking force based on the desired braking force and the first braking force includes: Determine the difference between the desired braking force and the first braking force; Since the braking force difference is a positive number, the braking force difference is used as the second braking force.

4. The method according to claim 1, characterized in that, The step of determining the first initial braking force and the second initial braking force based on the first target braking force and the preset front and rear braking force distribution curve includes: Obtain the first curve formula and the second curve formula corresponding to the preset front and rear braking force distribution curve. The first curve formula represents the relationship between the front wheel braking force, the rear wheel braking force and the ground adhesion coefficient and the vehicle mass. The second curve formula represents the relationship between the front wheel braking force and the rear wheel braking force and the ground adhesion coefficient and the vehicle size. Based on the first target braking force and the first curve formula, the first initial braking force is obtained; Based on the first target braking force and the second curve formula, the second initial braking force is obtained.

5. The method according to claim 1, characterized in that, The step of determining the second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold includes: Determine whether the difference is less than the preset difference threshold to obtain a first determination result; If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is not less than a preset difference threshold, then the braking force set is selected as the new first target braking force, which is greater than and adjacent to the first target braking force. Then, the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force is executed based on the first target braking force and the preset front and rear braking force distribution curve. If the first judgment result indicates that the difference between the first initial braking force and the second initial braking force is less than a preset difference threshold, the first initial braking force and the second initial braking force are recorded, and the preset difference threshold is updated based on the difference. Determine whether the first target braking force is the same as the first braking force, and obtain the second determination result; If the second judgment result indicates that the first target braking force is different from the first braking force, select the one that is greater than and adjacent to the first target braking force in the braking force set as the new first target braking force, and perform the step of determining the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve; If the second judgment result indicates that the first target braking force is the same as the first braking force, the average of the recorded first initial braking force and the second initial braking force is taken to obtain the second target braking force.

6. The method according to claim 1, characterized in that, The acquisition of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can recover includes: Receive the brake pedal opening; based on the correspondence between the pedal opening and the braking force, determine the desired braking force corresponding to the brake pedal opening; Obtain the vehicle mass and road surface adhesion coefficient; determine the vehicle weight based on the vehicle mass; obtain the vehicle's maximum ground adhesion force based on the vehicle weight and the road surface adhesion coefficient; Obtain the motor speed, final drive ratio, and tire radius; determine the maximum braking force the motor can provide based on the motor speed; determine the maximum braking force the motor can provide based on the maximum braking force the motor can provide and the final drive ratio and tire radius; Obtain the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius; based on the upper limit of battery charging power, motor power generation efficiency, motor current speed, main reduction ratio, and tire radius, determine the maximum regenerative braking force of the battery.

7. A vehicle brake force distribution device, characterized in that, include: The module is used to obtain the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate. The selection module is used to select one of the desired braking force, the vehicle's maximum ground adhesion, the maximum braking force that the motor can provide, and the maximum braking force that the battery can regenerate as the first braking force, which meets a preset lower limit condition. The first braking force is used to enable the electric braking system to control the wheel braking. The determination module is used to determine the front wheel braking force and the rear wheel braking force of the electric braking system based on the first braking force and the ground adhesion coefficient. The determining module includes: The setting unit is used to set a braking force set with 0 as the lower limit and the first braking force as the upper limit, according to a preset step size. The braking force set includes at least two target braking forces arranged in ascending order. The selection unit is used to select one of the braking forces in the set of braking forces in ascending order as the first target braking force; The first determining unit is used to determine the first initial braking force and the second initial braking force corresponding to the first target braking force based on the first target braking force and the preset front and rear braking force distribution curve, wherein the preset front and rear braking force distribution curve is related to the ground adhesion coefficient. The second determining unit is used to determine the second target braking force based on the difference between the first initial braking force and the second initial braking force and a preset difference threshold. The third determining unit is used to use the second target braking force as the rear wheel braking force and the first target braking force corresponding to the second target braking force as the front wheel braking force.

8. A vehicle-mounted controller, characterized in that, include: Memory, processor; The memory stores the processing program; The processor is used to load and execute the processing program stored in the memory to implement the steps of the vehicle braking force distribution method as described in any one of claims 1-6.

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