Vehicle control method and vehicle

Abstract

This application discloses a vehicle control method and a vehicle, relating to the field of vehicle control technology. The method includes: acquiring a target braking force for the entire vehicle and an upper limit of a first target axle braking force; when the target braking force is less than or equal to the upper limit of the first target axle braking force, controlling the first target axle braking force to equal the target braking force for the entire vehicle; when the target braking force is greater than the upper limit of the first target axle braking force, controlling the first target axle braking force to maintain it at the upper limit, and controlling the second target axle braking force so that the sum of the second target axle braking force and the first target axle braking force equals the target braking force for the entire vehicle. This method allows the first target axle to independently bear the vehicle's braking force when the first target axle braking force is below its upper limit, reducing the additional impact of the second target axle braking force on vehicle pitch; and when the first target axle braking force reaches its upper limit, the second target axle supplements the remaining braking force, ensuring that the vehicle's braking force meets the driver's needs.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and in particular to a vehicle control method and a vehicle. Background Technology

[0002] During vehicle braking, the distribution of braking force on the front first target axle affects braking performance and vehicle attitude. Under certain braking conditions, the braking force on the second target axle accounts for a larger proportion, which may cause the vehicle to jerk, affecting passenger comfort. Simultaneously, the braking force distribution must also consider road surface adhesion conditions and the load on the first target axle to prevent the first target axle from locking up and to maintain vehicle braking performance. Summary of the Invention

[0003] This application provides a vehicle control method and a vehicle, the purpose of which is to adjust the braking force distribution of the front first target axle according to the first target axle load and road adhesion conditions during braking.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] A vehicle control method, comprising:

[0006] Obtain the vehicle's overall target braking force and the upper limit of the first target axle braking force;

[0007] When the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be equal to the target braking force of the whole vehicle.

[0008] When the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be maintained at the upper limit of the first target axle braking force, and the second target axle braking force of the vehicle is controlled so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle.

[0009] A vehicle includes: a processor, a memory, and a bus; the processor and the memory are connected via the bus.

[0010] The memory is used to store a program, and the processor is used to run the program, wherein the program is executed by the processor to perform the vehicle control method described above.

[0011] The technical solution provided in this application compares the target braking force of the whole vehicle with the upper limit of the braking force of the first target axle. When the target braking force of the whole vehicle is less than or equal to the upper limit of the braking force of the first target axle, the first target axle independently bears the braking force of the whole vehicle, reducing the additional impact of the braking force of the second target axle on the vehicle pitch, and cooperating with the suspension adjustment to suppress vehicle jerking. When the target braking force of the whole vehicle is greater than the upper limit of the braking force of the first target axle, the first target axle maintains the upper limit of the braking force of the first target axle, and the second target axle supplements the remaining braking force to ensure that the braking force of the whole vehicle meets the driver's needs. Thus, without relying on a preset fixed braking force distribution curve, both braking comfort and braking safety are taken into account. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a first flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0014] Figure 2 This is a second flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0015] Figure 3 A third flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0016] Figure 4 A fourth flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0017] Figure 5 A fifth flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0018] Figure 6 A sixth flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0019] Figure 7 A seventh flowchart illustrating a vehicle control method provided in an embodiment of this application;

[0020] Figure 8 The eighth flowchart of a vehicle control method provided in this application embodiment;

[0021] Figure 9 A schematic diagram of the architecture of a vehicle electromechanical braking system provided in this application embodiment;

[0022] Figure 10 This is a schematic diagram of the architecture of a vehicle provided in an embodiment of this application. Detailed Implementation

[0023] 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 skilled in the art without creative effort are within the scope of protection of this application.

[0024] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0025] like Figure 1 The diagram shown is a first flowchart of a vehicle control method provided in an embodiment of this application, applied to a vehicle system, and includes the following steps.

[0026] S101: Obtain the vehicle's overall target braking force and the upper limit of the first target axle braking force.

[0027] The target braking force of the whole vehicle is the total braking force required by the vehicle during the current braking process, which can be determined based on the driver's operation of the brake pedal. The upper limit of the first target axle braking force is the maximum braking force that the vehicle's first target axle can output under the current road surface conditions.

[0028] In this embodiment of the application, the first target axle is the rear axle of the vehicle, and the second target axle is the front axle of the vehicle.

[0029] In some examples, the vehicle control method provided in this application can be applied to an electromechanical braking system. Specifically, see... Figure 9The diagram illustrates the architecture of a vehicle's electromechanical braking system. An electromechanical braking system typically consists of an electronic brake pedal, a central domain controller, and four EMB (Electro Mechanical Brake) calipers. EMB offers advantages such as timely response, compact structure, low drag torque, and high controllability. Each of the four EMB calipers independently controls one of the vehicle's four wheels: the left front EMB caliper controls the left front wheel, the right front EMB caliper controls the right front wheel, the left rear EMB caliper controls the left rear wheel, and the right rear EMB caliper controls the right rear wheel. By utilizing its ability to independently control all four wheels, EMB can achieve ideal braking force distribution and more fully utilize the road surface's coefficient of friction.

[0030] Specifically, the electronic brake pedal collects the driver's braking needs and transmits these needs to the central domain controller. The central domain controller controls the EMB calipers to perform brake clamping or releasing actions via communication methods such as CAN (Controller Area Network). The EMB calipers integrate a brake drive motor and wheel-end controllers. The wheel-end EMB controllers control the brake motors to clamp or release the calipers to achieve braking actions. Because a single EMB caliper is located far from the driver and passengers at the wheel end and produces low braking noise, and because the EMB architecture allows for completely independent braking of all four wheels, the EMB system can more flexibly implement brake force distribution functions.

[0031] In related technologies, the comfort braking function of hydraulic braking systems typically increases braking comfort at low vehicle speeds by adjusting the internal braking pressure to be lower than the driver's braking demand, thereby appropriately extending the braking distance. However, this function is limited to low speeds and cannot suppress the braking jerkiness issue throughout the braking process. While EMB (Electronic Braking Management) utilizes the ideal I-curve for front first target axle braking force distribution to fully leverage road adhesion for braking, it also cannot suppress the braking jerkiness issue throughout the braking process. Therefore, this application's embodiment compares the overall vehicle target braking force with the upper limit of the first target axle braking force. Under non-emergency braking conditions, the first target axle prioritizes bearing the overall vehicle braking force, suppressing vehicle jerkiness from the initial braking stage and thus improving braking comfort throughout the entire braking process.

[0032] It should be noted that the target braking force of the entire vehicle can be determined based on the brake pedal travel signal; the greater the brake pedal travel, the greater the target braking force of the entire vehicle. The upper limit of the first target axle braking force is not a fixed value, but varies with vehicle load and road adhesion conditions, therefore it needs to be acquired in real time during each braking process.

[0033] It should be noted that the method in this application embodiment is not only applicable to electromechanical braking systems, but also to other brake-by-wire systems that can achieve independent control of the braking force of the first target axle.

[0034] Optionally, the process for obtaining the upper limit of the first target axle braking force of the vehicle can be found in [reference needed]. Figure 2 The steps shown are explained below.

[0035] S102: When the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be equal to the target braking force of the whole vehicle.

[0036] When the target braking force of the whole vehicle is less than or equal to the upper limit of the braking force of the first target axle, it indicates that the first target axle can independently bear the braking demand of the whole vehicle under the current driving road conditions. At this time, the braking force of the first target axle is controlled to be equal to the target braking force of the whole vehicle, and the second target axle does not output braking force, so that the braking force of the whole vehicle is borne entirely by the first target axle.

[0037] In some examples, when the vehicle is braking on a high-traction surface and with slight deceleration, the initial braking force is increased only on the rear wheels while maintaining the rear wheel braking force equal to the total braking demand from the driver. This achieves comfortable deceleration without sacrificing vehicle speed. Subsequently, based on the initial target axle load confirming sufficient road surface traction, the rear wheel braking force is continuously increased to achieve comfortable deceleration.

[0038] In one possible implementation, when the target braking force of the entire vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force F μ2 Equal to the vehicle's target braking force F μ总 Second target axis braking force F μ1 =0. Since the entire braking force of the vehicle is borne by the first target axle, the load transfer of the second target axle is reduced during braking, which reduces the additional impact of the second target axle braking force on the vehicle pitch and improves braking comfort.

[0039] It should be noted that "the second target axle does not output braking force" means that the brake actuator of the second target axle does not generate braking clamping force, not that the second target axle is completely unloaded; the second target axle still bears the vertical load. When the second target axle does not output braking force, all the braking force of the vehicle is borne by the first target axle. At this time, the vehicle deceleration relies entirely on the adhesion between the first target axle and the road surface. Therefore, accurately determining the upper limit of the braking force of the first target axle is crucial to ensuring braking performance and safety.

[0040] In this embodiment, when the first target axle independently bears the braking force of the entire vehicle, the load transfer to the second target axle is reduced because the braking force is concentrated on the first target axle. This reduces the compression of the front suspension and minimizes the additional impact of the second target axle's braking force on the vehicle's pitch. Simultaneously, since the entire braking force is provided by the first target axle, the adhesion between the first target axle and the road surface is fully utilized. Therefore, braking force distribution needs to be performed within the adhesion limit range of the first target axle to ensure braking safety.

[0041] Optionally, before controlling the first target axle braking force of the vehicle to equal the overall vehicle braking force when the target braking force of the entire vehicle is less than or equal to the upper limit of the first target axle braking force, this embodiment of the application further performs a precondition determination for this step. The specific determination process can be found in [reference needed]. Figure 5 The steps shown are explained below.

[0042] Optionally, when controlling the braking force of the first target axle of the vehicle to be equal to the target braking force of the entire vehicle, the embodiments of this application also simultaneously control the operation of the suspension actuators of the second target axle and the first target axle. The specific implementation process can be found in [reference needed]. Figure 7 The steps shown are explained below.

[0043] S103: When the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, control the first target axle braking force of the vehicle to maintain at the upper limit of the first target axle braking force, and control the second target axle braking force of the vehicle so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle.

[0044] When the target braking force of the whole vehicle is greater than the upper limit of the braking force of the first target axle, it indicates that the first target axle cannot independently bear the braking demand of the whole vehicle under the current driving road conditions. At this time, the braking force of the first target axle is controlled to be maintained at the upper limit of the first target axle braking force, and the insufficient part is supplemented by the braking force of the second target axle.

[0045] In some examples, when the total braking demand continues to increase, the F requirement is not met. μ总 ≤0.9×F rear (Represents the vehicle's first target axle load) × When the condition (representing the road surface adhesion parameters of the current driving surface) is met, increase the braking force of the second target axle while maintaining the braking force of the first target axle F. μ2 The increase in braking force ΔF of the second target axis remains unchanged. μ1 =F μ总 -F μ2 At this moment, the braking force F of the first target axis μ2 Maintain at the upper limit of the first target axle braking force, and the second target axle braking force F μ1 Equal to the vehicle's target braking force F μ总Subtract the braking force F of the first target axis μ2 .

[0046] In one possible implementation, when the target braking force of the vehicle decreases from greater than the upper limit of the first target axle braking force to less than or equal to the upper limit of the first target axle braking force, the second target axle braking force is controlled to decrease to zero, and the first target axle braking force is controlled to be equal to the target braking force of the vehicle, that is, the vehicle returns to the state where the first target axle independently bears the braking force of the vehicle.

[0047] It should be noted that maintaining the first target axle braking force at its upper limit means that the first target axle braking force is kept at the maximum braking force that the first target axle can output under the current road surface adhesion conditions, and will not continue to increase, in order to avoid the first target axle locking up. The sum of the second target axle braking force and the first target axle braking force equals the total vehicle target braking force, ensuring that the total output of the vehicle's braking force meets the driver's needs and that braking performance is not reduced due to the switching of the braking force distribution strategy.

[0048] In this embodiment, when the target braking force of the vehicle exceeds the upper limit of the braking force of the first target axle, the increase in the braking force of the second target axle is equal to the difference between the target braking force of the vehicle and the braking force of the first target axle, thereby ensuring that the braking force of the vehicle is always equal to the driver's needs and that the braking performance of the vehicle will not be reduced due to the first target axle reaching the adhesion limit.

[0049] The process described in S101-S103 above compares the target braking force of the whole vehicle with the upper limit of the braking force of the first target axle. When the target braking force of the whole vehicle is less than or equal to the upper limit of the braking force of the first target axle, the first target axle independently bears the braking force of the whole vehicle, reducing the load transfer of the second target axle and reducing the additional impact of the braking force of the second target axle on the vehicle pitch. When the target braking force of the whole vehicle is greater than the upper limit of the braking force of the first target axle, the first target axle maintains the upper limit of the braking force of the first target axle, and the second target axle supplements the remaining braking force, ensuring that the braking force of the whole vehicle meets the needs of the driver, thereby taking into account both braking comfort and braking safety.

[0050] like Figure 2 The diagram shown is a second flowchart of a vehicle control method provided in an embodiment of this application, including the following steps.

[0051] S201: Obtain the vehicle's first target axle load and the road surface adhesion parameters of the current driving surface.

[0052] Among them, the first target axle load is the vertical load on the first target bearing of the vehicle, and the road surface adhesion parameters are parameters characterizing the current road surface adhesion capability.

[0053] In some examples, the first target axle load can be obtained in real time by the vehicle's electronically controlled suspension by detecting the load distribution of the second target axle and the first target axle.

[0054] Specifically, the second target shaft load F front =C1×S1, First target shaft load F rear =C2×S2, where C1 represents the real-time stiffness of the second target axle suspension, C2 represents the real-time stiffness of the first target axle suspension, S1 represents the displacement of the second target axle suspension, and S2 represents the displacement of the first target axle suspension. The real-time stiffness of the front first target axle suspension can be obtained through sensor signals inside the electronically controlled suspension, and the displacement of the front first target axle suspension can be obtained through a suspension height sensor. The suspension height sensor is installed on the vehicle suspension system and is used to detect the displacement of the suspension relative to the vehicle body.

[0055] In some examples, road surface adhesion parameters can be obtained by identifying the type of road surface the vehicle is traveling on using the vehicle's intelligent driving cameras. Road surface types include asphalt, cement, rough roads, mud and sand, snow, ice, and slippery surfaces. Based on the road surface type provided by the intelligent driving system, the system database determines the road surface adhesion parameters for the vehicle at that moment.

[0056] It should be noted that the first target axle load includes the portion of the vehicle's own weight distributed to the first target axle, as well as the load transferred to the first target axle due to inertia during braking. Road surface adhesion parameters refer to the ratio of the maximum adhesion force that the road surface can provide to the tires to the vertical load; their value range is typically [0,1], with a larger value indicating stronger road surface adhesion.

[0057] In this embodiment, the load on the first target axle can be calculated in real time using sensor signals from the electronically controlled suspension, eliminating the need for an additional load sensor and thus reducing system costs. Road surface adhesion parameters can be obtained by querying the system database after the intelligent driving camera identifies the road surface type, fully utilizing the vehicle's existing intelligent driving perception equipment without requiring additional sensors.

[0058] Optionally, the process of obtaining the vehicle's first target axle load and the road adhesion parameters of the current driving surface can be found in [reference needed]. Figure 3 The steps shown are explained below.

[0059] S202: Determine the upper limit of the braking force of the first target axle based on the first target axle load and road surface adhesion parameters.

[0060] The upper limit of the braking force of the first target axle is determined based on the load of the first target axle and the road surface adhesion parameters, and represents the maximum braking force that the first target axle can output under the current load and road surface adhesion conditions.

[0061] In some examples, the upper limit of the braking force of the first target axle is determined as follows: the adhesion limit of the first target axle is determined based on the load of the first target axle and the road surface adhesion parameters, and the product of the adhesion limit of the first target axle and a preset coefficient is determined as the upper limit of the braking force of the first target axle.

[0062] In one possible implementation, the braking force of the first target axis satisfies F μ总 =F μ2 ≤0.9×F rear × At this time, the braking force on the first target axle can be continuously increased. Here, 0.9 represents a preset coefficient used for redundancy to prevent the first target axle from locking up and drifting. If the strategy is applied at the critical value, there is a chance that the rear wheels may activate anti-lock braking or lock up and drift, thus a certain degree of redundancy is provided.

[0063] It should be noted that the adhesion limit of the first target axle refers to the maximum ground braking force that the first target axle can transmit under the current load and road adhesion parameters. Its value is equal to the product of the load of the first target axle and the road adhesion parameters. The preset coefficient is less than 1 to reserve a safety margin based on the adhesion limit, so as to avoid locking up due to slight changes in road conditions when the braking force of the first target axle reaches the adhesion limit.

[0064] In this embodiment, the preset coefficient is set to 0.9, which strikes a balance between fully utilizing the adhesion capability of the first target axle and ensuring braking safety. If the preset coefficient is too large, the braking force of the first target axle may approach the adhesion limit, posing a risk of wheel lock-up; if the preset coefficient is too small, the upper limit of the braking force of the first target axle is too low, reducing the applicability of the first target axle priority strategy and limiting the improvement in braking comfort.

[0065] Optionally, the process for determining the upper limit of the first target axle braking force based on the first target axle load and road surface adhesion parameters can be found in [reference needed]. Figure 4 The steps shown are explained below.

[0066] Optionally, embodiments of this application may also dynamically update the upper limit of the braking force of the first target axle based on the real-time load of the vehicle's first target axle. The specific implementation process can be found in [reference needed]. Figure 8 The steps shown are explained below.

[0067] The process shown in S201-S202 above obtains the first target axle load and road surface adhesion parameters, and determines the upper limit of the first target axle braking force based on the two. This provides an accurate basis for comparing the subsequent vehicle target braking force with the upper limit of the first target axle braking force, thereby ensuring that the first target axle priority strategy can be implemented safely and effectively under different load and road surface conditions.

[0068] like Figure 3 The diagram shown is a third flowchart of a vehicle control method provided in an embodiment of this application, including the following steps.

[0069] S301: Obtain the suspension displacement signal of the second target axle and the suspension displacement signal of the first target axle of the vehicle through the vehicle's suspension sensor.

[0070] The suspension sensor is a sensor installed on the vehicle's suspension system to collect suspension displacement signals. The second target axle suspension displacement signal represents the displacement of the second target axle suspension, and the first target axle suspension displacement signal represents the displacement of the first target axle suspension.

[0071] In some examples, the suspension displacement of the front first target axle can be obtained using a suspension height sensor. The suspension height sensor is located on the vehicle's suspension system and is used to detect the amount of displacement of the suspension relative to the vehicle body.

[0072] In one possible implementation, the second target axle suspension displacement signal corresponds to the second target axle suspension displacement S1, and the first target axle suspension displacement signal corresponds to the first target axle suspension displacement S2.

[0073] It should be noted that the suspension displacement signal refers to the change in height of the suspension system relative to the vehicle body, which reflects the compression or extension state of the suspension. The suspension sensor can be a suspension height sensor or other sensors capable of detecting suspension displacement; this application does not limit the specific type of sensor used.

[0074] S302: Determine the first target axle load of the vehicle based on the second target axle suspension displacement signal and the first target axle suspension displacement signal.

[0075] The first target axle load is determined based on the second target axle suspension displacement signal and the first target axle suspension displacement signal.

[0076] In some examples, the first target shaft load F rear =C2×S2, where C2 is the vertical stiffness of the suspension on the first target axle, and S2 is the displacement of the suspension on the first target axle. The real-time stiffness of the suspension on the first target axle can be obtained through the sensor signals inside the electronically controlled suspension.

[0077] In one possible implementation, the real-time axle load of the first target axle can be calculated by combining the second target axle suspension displacement signal and the first target axle suspension displacement signal with the vertical stiffness of the first target axle suspension, thereby determining the first target axle load.

[0078] It should be noted that suspension vertical stiffness refers to the force required for the suspension system to generate a unit displacement in the vertical direction, which can be obtained through signals from sensors inside the electronically controlled suspension. The determination of the first target axle load is not limited to using only the first target axle suspension displacement signal; it can also be combined with the second target axle suspension displacement signal for load transfer calculation to improve accuracy.

[0079] In this embodiment, the load of the first target axle is determined by the displacement signal of the first target axle suspension, which can more accurately reflect the load change caused by inertial transfer during braking, thereby improving the calculation accuracy of the upper limit of the braking force of the first target axle.

[0080] S303: Obtain information about the type of road surface being traveled through the vehicle's environmental sensing device.

[0081] Among them, the environmental perception device is a device installed on the vehicle to perceive the external environment, and the type information represents the type of the current road surface.

[0082] In some examples, the environmental perception device can be a vehicle-wide intelligent driving camera. The camera identifies the type of road surface the vehicle is traveling on, such as asphalt, cement, rough roads, mud, snow, ice, and slippery surfaces, and provides the identification results to the braking system. Based on the identified road surface type, the braking system queries the pre-stored correspondence between road surface types and road adhesion parameters in the system database to determine the road adhesion parameters the vehicle is currently traveling on.

[0083] In one possible implementation, the camera captures images of the road surface and uses an image recognition algorithm to determine the type of road surface being driven on.

[0084] In some examples, the environmental sensing device is not limited to cameras, but can also be devices capable of sensing road surface type, such as lidar and millimeter-wave radar. Road surface type information can be a classification result of road surface material, such as asphalt, cement, snow, ice, etc., or it can be grade information that directly characterizes the road surface's adhesion ability.

[0085] It should be noted that by identifying the road surface type through the environmental perception device and querying the system database to determine the road surface adhesion parameters, the vehicle's existing intelligent driving perception equipment can be fully utilized without the need to add additional road surface adhesion sensors, thereby reducing system costs and improving system integration.

[0086] S304: Determine the road surface adhesion parameters of the current driving surface based on the type information.

[0087] Among them, the road surface adhesion parameters are determined based on the road surface type information.

[0088] In some examples, the system determines the road surface adhesion parameters of the vehicle based on the road surface type provided by the intelligent driving system and its database. The system database stores the correspondence between various road surface types and road surface adhesion parameters.

[0089] In one possible implementation, when the road surface type is ice, the corresponding road surface adhesion parameters are lower; when the road surface type is asphalt, the corresponding road surface adhesion parameters are higher.

[0090] It should be noted that the correspondence in the system database can be obtained through actual vehicle testing and calibration. Different road surface types correspond to different ranges of road surface adhesion parameters. The road surface adhesion parameters can be used to subsequently calculate the adhesion limit of the first target axle and the upper limit of the braking force of the first target axle.

[0091] The processes shown in S301-S304 above obtain the suspension displacement signal of the first target axle through the suspension sensor to determine the load of the first target axle, and obtain road surface type information through the environmental sensing device to determine the road surface adhesion parameters, thus providing an accurate data basis for determining the upper limit of the braking force of the first target axle.

[0092] Optionally, based on the aforementioned road surface adhesion parameters and the first target axle load, the braking force distribution control strategy of this application embodiment can be summarized as follows: determining whether the road surface adhesion coefficient meets the conditions; real-time detection of the load distribution of the second target axle and the first target axle through electronically controlled suspension; distributing and coordinating the intervention and adjustment of the front first target axle suspension according to the ideal I curve in low-adhesion or complex road surfaces or emergency braking scenarios; increasing the rear wheel braking force output in high-adhesion road surfaces and small deceleration scenarios; increasing the second target axle braking force when the total braking demand continues to increase and the conditions are not met; switching when the vehicle switches from a small deceleration state to a low-adhesion or emergency braking scenario, and only allowing one switch. The specific implementation process of the above control strategy can be found in [reference needed]. Figures 5 to 8 The steps shown are explained below.

[0093] like Figure 4 The diagram shown is a fourth flowchart of a vehicle control method provided in an embodiment of this application, including the following steps.

[0094] S401: Determine the adhesion limit of the first target axle based on the first target axle load and road surface adhesion parameters.

[0095] The adhesion limit of the first target axis is the maximum ground braking force that the first target axis can transmit under the current load and road surface adhesion conditions.

[0096] In some examples, the adhesion limit of the first target axle is determined based on the product of the first target axle load and the road surface adhesion parameters. The larger the first target axle load and the higher the road surface adhesion parameters, the greater the adhesion limit of the first target axle.

[0097] In one possible implementation, the adhesion limit of the first target axis can be expressed as F. rear × F rear The first target shaft load, These are the road surface adhesion parameters.

[0098] It should be noted that the adhesion limit refers to the maximum longitudinal force that can be transmitted between the tire and the road surface. Exceeding this limit will cause the tire to lock up or slip. The adhesion limit of the first target axle determines the maximum braking force that the first target axle can provide without locking up.

[0099] S402: The product of the adhesion limit of the first target axis and the preset coefficient is determined as the upper limit of the braking force of the first target axis.

[0100] The preset coefficient is less than 1, which is used to provide safety redundancy for the braking force of the first target axis and prevent the first target axis from locking up and drifting.

[0101] In some examples, the preset coefficient is set to 0.9. When the total braking force demand of the vehicle F... μ总 ≤0.9×F rear × At that time, the braking force F of the first target axis can be made μ2 Completely equal to F μ总 In other words, when the total braking force requirement is less than the non-locking adhesion force that the first target axle load can withstand, the braking force of the entire vehicle can be completely transferred to the first target axle, which is F. μ1 =0, F μ2 =F μ总 This reduces the additional impact of the second target axle braking force on vehicle pitch.

[0102] In one possible implementation, the preset coefficient is set to 0.9 because if the strategy is applied at the critical value, there is a chance that the rear wheels may activate anti-lock braking or engage in a fishtailing maneuver, mainly to provide some redundancy. The specific coefficient value can be calibrated based on the actual vehicle.

[0103] It should be noted that the preset coefficient is less than 1 to ensure that the braking force of the first target axle is always lower than the first target axle adhesion limit, thus avoiding the first target axle from locking up due to errors in road surface adhesion parameter estimation or load fluctuations. The specific value of the preset coefficient can be determined based on actual vehicle calibration and is not limited to 0.9.

[0104] The processes shown in S401-S402 above determine the upper limit of the braking force of the first target axis by multiplying it by a preset coefficient less than 1 based on the first target axis adhesion limit. This provides a safety boundary for the first target axis priority strategy, ensuring that the first target axis works within the adhesion limit and preventing the first target axis from locking up and drifting.

[0105] like Figure 5 The diagram shown is a fifth flowchart of a vehicle control method provided in an embodiment of this application, including the following steps.

[0106] S501: Obtain the vehicle's braking urgency and the road surface adhesion parameters of the current driving surface.

[0107] Among them, the braking urgency level characterizes the urgency of the driver's current braking operation, and the road surface adhesion parameter characterizes the adhesion capability of the current road surface.

[0108] In some examples, the urgency of braking can be determined by the average depressing speed during the initial travel of the brake pedal. An average depressing speed of ≥10mm / s during the initial travel of the brake pedal is considered emergency braking, while an average depressing speed of <10mm / s during the initial travel of the brake pedal is considered non-emergency braking. Specific calibration should be performed based on the actual vehicle.

[0109] In one possible implementation, the road surface adhesion parameters can be obtained in the manner described in S303-S304 above.

[0110] It should be noted that the urgency of braking can be characterized by parameters such as the brake pedal depressing speed and the rate of change of brake pedal travel. The average depressing speed during the initial stage of the brake pedal travel refers to the average pedal speed during the initial phase (e.g., within 3mm of travel) after the driver begins to depress the brake pedal, which can reflect the driver's urgent braking intention.

[0111] In this embodiment, the braking urgency is determined by the average depressing speed during the initial travel of the brake pedal. This allows for the identification of the driver's braking intention at the initial stage of braking, enabling timely adjustment of the braking force distribution strategy and preventing prolonged braking distance due to the first target axle priority strategy in emergency braking scenarios.

[0112] S502: When the road surface adhesion parameter is greater than the preset adhesion parameter threshold and the braking urgency is less than the preset urgency threshold, the vehicle is determined to be in the first working condition.

[0113] The first working condition is a working condition where the road surface adhesion parameter is greater than the preset adhesion parameter threshold and the braking urgency is less than the preset urgency threshold, that is, a working condition with high adhesion road surface and non-emergency braking.

[0114] In some examples, the vehicle is identified as being in the first operating condition when it is on a high-adhesion road surface and braking with slight deceleration.

[0115] In one possible implementation, a first target axle priority strategy is executed under the first operating condition, that is, when the vehicle target braking force is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force is controlled to be equal to the vehicle target braking force.

[0116] It should be noted that the preset adhesion parameter threshold and preset urgency threshold can be determined based on actual vehicle calibration. The first operating condition corresponds to a scenario with high adhesion road surface and non-emergency braking by the driver. In this case, the first target axle priority strategy can reduce the additional impact of the second target axle braking force on vehicle pitch while ensuring safety.

[0117] S503: When the road surface adhesion parameter is less than or equal to the preset adhesion parameter threshold or the braking emergency level is greater than or equal to the preset emergency level threshold, the vehicle is determined to be in the second working condition.

[0118] The second working condition is a working condition where the road surface adhesion parameter is less than or equal to the preset adhesion parameter threshold or the braking urgency is greater than or equal to the preset urgency threshold, i.e., a working condition with low adhesion road surface or emergency braking.

[0119] In some examples, low road adhesion is defined as a road adhesion parameter ≤ 0.3, typically on snow or ice. Complex road surface is a mixed high and low adhesion road surface, i.e., a condition where the road adhesion parameter changes during vehicle movement. Emergency braking scenario is defined as a condition where the average initial braking speed is ≥ 10 mm / s.

[0120] In one possible implementation, under the second operating condition, the braking force of the first target axle before the EMB is distributed according to the ideal I curve, so as to make more reasonable use of the road surface adhesion, improve the deceleration utilization rate, and implement more effective deceleration.

[0121] It should be noted that the second working condition corresponds to low-adhesion road surfaces or emergency braking scenarios. In this case, it is necessary to prioritize braking safety and braking efficiency. Therefore, the braking force of the first target axle is distributed according to the preset front and rear braking force distribution curve to make full use of the road surface adhesion.

[0122] In this embodiment, by using road surface adhesion parameters and braking urgency as the basis for dividing operating conditions, different braking force distribution strategies can be adopted under different braking scenarios, thereby balancing braking comfort and braking safety. Specifically, braking comfort is prioritized in the first operating condition, while braking safety is prioritized in the second operating condition.

[0123] S504: When the vehicle is in the first operating condition, the following steps are performed: when the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is equal to the target braking force of the whole vehicle; when the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is maintained at the upper limit of the first target axle braking force, and the second target axle braking force of the vehicle is controlled so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle.

[0124] In the first operating condition, a first target axle priority strategy is implemented. When the target braking force of the entire vehicle is less than or equal to the upper limit of the first target axle braking force, the braking force of the first target axle is controlled to be equal to the target braking force of the entire vehicle; when the target braking force of the entire vehicle is greater than the upper limit of the first target axle braking force, the braking force of the first target axle is controlled to be maintained at the upper limit of the first target axle braking force, and the insufficient part is supplemented by the second target axle braking force, so that the sum of the second target axle braking force and the first target axle braking force equals the target braking force of the entire vehicle.

[0125] In some examples, when the vehicle is on a high-friction surface and braking with slight deceleration, only the braking force output of the rear wheels is increased in the initial stage of braking, while keeping the braking force of the rear wheels equal to the total braking demand of the driver. This can achieve comfortable deceleration without losing vehicle deceleration.

[0126] Optionally, when the vehicle is in the first operating condition, and the vehicle switches from the first operating condition to the second operating condition during a single braking process, the target braking force of the second target axle and the target braking force of the first target axle are determined according to the preset front and rear braking force distribution curve. The vehicle's second target axle braking force is controlled to be equal to the target braking force of the second target axle, and the vehicle's first target axle braking force is equal to the target braking force of the first target axle. During a single braking process, the vehicle's second target axle braking force is kept equal to the target braking force of the second target axle, and the vehicle's first target axle braking force is kept equal to the target braking force of the first target axle.

[0127] During a single braking operation, the vehicle may transition from a first operating condition to a second operating condition. For example, the vehicle may move from a high-traction surface to a low-traction surface during braking, or the driver may perform an emergency braking operation. In this situation, if the first target axle priority strategy is maintained, the first target axle may lock up due to insufficient traction. Therefore, it is necessary to switch the braking force distribution strategy from prioritizing the first target axle to distributing braking force according to a preset front and rear braking force distribution curve to prioritize braking safety.

[0128] During a single braking operation, when the vehicle switches from the first operating condition to the second operating condition, only one switch is allowed, and it will not revert to the first operating condition after the switch, in order to avoid repeated strategy switching affecting ride comfort. If repeated switching were allowed, when the road surface adhesion parameters fluctuate near the threshold or the driver's braking operation is unstable, the braking force distribution strategy may switch between the first and second operating conditions multiple times, causing repeated changes in the braking force of the front first target axle, which in turn causes fluctuations in vehicle deceleration and changes in vehicle body posture, affecting ride comfort. Therefore, during a single braking operation, once the vehicle switches from the first operating condition to the second operating condition, it maintains the pre-set front and rear braking force distribution curve and will not revert to the first operating condition.

[0129] It should be noted that only one switching is allowed during a single braking process, and there is no reversal. This is to avoid repeated switching of the braking force distribution strategy due to fluctuations in road surface adhesion parameters near the threshold or unstable driver braking operations. Repeated switching of the strategy will cause repeated changes in the braking force on the front first target axle, which in turn will lead to fluctuations in vehicle deceleration and changes in vehicle posture, affecting ride comfort.

[0130] Optionally, when determining the target braking force of the second target axle and the target braking force of the first target axle based on the preset front and rear braking force distribution curve, this embodiment of the application can also control the vehicle to adjust the state of the second target axle suspension based on the second target axle target braking force. For details of the control process, please refer to [link to relevant documentation]. Figure 6 The steps shown are explained below.

[0131] It should also be noted that the first target axle priority strategy under the first operating condition means that the first target axle should bear the vehicle's braking force first, so as to reduce the load transfer of the second target axle and thus reduce the additional impact of the second target axle's braking force on the vehicle's pitch. When the vehicle's target braking force exceeds the upper limit of the first target axle's braking force, the second target axle will supplement the remaining braking force to ensure that the vehicle's braking force meets the driver's needs.

[0132] S505: When the vehicle is in the second operating condition, the target braking force of the second target axle and the target braking force of the first target axle are determined according to the preset front and rear braking force distribution curve, and the target braking force of the second target axle is controlled to be equal to the target braking force of the second target axle and the target braking force of the first target axle is controlled to be equal to the target braking force of the first target axle.

[0133] In the second operating condition, the braking force of the first target axle is distributed according to the preset front and rear braking force distribution curve.

[0134] In some examples, the preset front and rear braking force distribution curve is the ideal I curve. The ideal I curve is a braking technical term; the normal term is "ideal front and rear brake force distribution curve." Its distribution method mainly refers to the conclusions and distribution formulas of the vehicle's front and rear wheels locking simultaneously under adhesion conditions in automotive theory to distribute braking force. EMB can achieve this distribution through independent front and rear braking.

[0135] Specifically, the ideal I-curve can be determined as follows: the braking forces of the front and rear wheel brakes are F... μ1 F μ2 The adhesion coefficient is The distance from the car's center of mass to the center line of the second target axis is 'a', the car's weight is 'G', the horizontal distance from the car's center of mass to the center line of the first target axis is 'b', and the height of the car's center of mass is 'h'. g Based on the condition that the front and rear wheels of the vehicle lock up simultaneously, the braking force of the brake on the first target axle must satisfy F. μ1 +F μ2 = G, and the ratio of the braking force of the first target axis to F satisfies μ1 / F μ2 =(b+ h g ) / (a- h gThis allows us to determine the target braking force for the second target axis and the target braking force for the first target axis at each point on the ideal I curve.

[0136] In some examples, the specific distribution of braking force of the first target axle brake can be summarized as follows:

[0137] (1).

[0138] In formula (1), L represents the wheelbase of the vehicle, i.e., L = a + b.

[0139] In one possible implementation, when the vehicle is on a low-adhesion or complex road surface, or when the vehicle is in an emergency braking scenario, the EMB braking system distributes the braking force of the first target axle of the EMB according to the ideal I curve, making more reasonable use of the road adhesion, improving the deceleration utilization rate, and implementing more effective deceleration. At the same time, in order to ensure the consistency of vehicle braking comfort, the suspension of the first target axle is coordinated to intervene and adjust, suppressing vehicle jerking.

[0140] It should be noted that the preset front and rear braking force distribution curve is not limited to the ideal I curve, but can also be other curves that can reasonably distribute the braking force of the front first target axle. In the second working condition, distributing the braking force of the front first target axle according to the preset front and rear braking force distribution curve can make fuller use of the road adhesion conditions and improve braking efficiency.

[0141] The processes shown in S501-S505 above, by acquiring braking urgency and road surface adhesion parameters, divide into a first working condition and a second working condition, execute a first target axis priority strategy in the first working condition, and distribute braking force according to a preset front and rear braking force distribution curve in the second working condition, thereby realizing adaptive adjustment of braking force distribution strategy according to different braking scenarios.

[0142] like Figure 6 The diagram shown is a sixth flowchart of a vehicle control method provided in an embodiment of this application, including the following steps.

[0143] S601: Obtain the vertical stiffness of the second target axle suspension of the vehicle.

[0144] Among them, the vertical stiffness of the second target axle suspension is the vertical stiffness of the second target axle suspension system.

[0145] In some examples, the vertical stiffness of the second target axis suspension can be obtained through sensor signals inside the electronically controlled suspension.

[0146] It should be noted that the vertical stiffness of the second target axle suspension refers to the force required for the second target axle suspension system to produce a unit displacement in the vertical direction, which can affect the degree of vehicle pitch during braking.

[0147] S602: Determine the target stiffness of the vehicle's second target axle suspension based on the target braking force of the second target axle.

[0148] The target stiffness of the second target axle suspension is determined based on the target braking force of the second target axle and is used to adjust the vertical stiffness of the second target axle suspension to suppress vehicle pitch when the braking force distribution is switched.

[0149] In some examples, when the vehicle switches from the first operating condition to the second operating condition, the braking force of the second target axle increases to the second target axle braking force distributed by the ideal I curve. In order to avoid sudden vehicle jerking that could cause passenger discomfort, the vertical stiffness of the second target axle suspension needs to be adjusted.

[0150] In one possible implementation, the greater the target braking force of the second target axle, the greater the target stiffness of the second target axle suspension, in order to provide greater suspension support force and suppress vehicle pitch.

[0151] It should be noted that the target stiffness of the second target axle suspension refers to the stiffness value that the second target axle suspension needs to be adjusted to in order to suppress vehicle pitch during braking force distribution switching. The larger the target braking force of the second target axle, the greater the braking force that the second target axle needs to provide. In order to suppress the resulting vehicle pitch, the target stiffness of the second target axle suspension should be increased accordingly.

[0152] S603: Controls the second target axle suspension of the vehicle to adjust the vertical stiffness of the second target axle suspension to the target stiffness of the second target axle suspension in order to suppress the vehicle pitch when the braking force distribution is switched.

[0153] Specifically, by adjusting the vertical stiffness of the second target axle suspension from the current stiffness to the target stiffness, the vehicle pitch is suppressed when the braking force distribution is switched.

[0154] In some examples, the displacements S1 and S2 that need to be adjusted for the front first target axle suspension are adjusted according to the torque balance relationship of the front first target axle suspension. Specifically, the torque balance relationship of the front first target axle suspension is as follows:

[0155] (2);

[0156] (3);

[0157] In formulas (2) and (3), C1 is the vertical stiffness of the second target axle suspension, C2 is the vertical stiffness of the first target axle suspension, S1 is the displacement of the second target axle suspension, S2 is the displacement of the first target axle suspension, ΔG is the load transfer, d1 is the lever arm of the second target axle suspension, d2 is the lever arm of the first target axle suspension, and F... μ1 For the second target axis braking force, F μ2Let e1 be the braking force of the first target axle, and e2 be the braking force arm of the first target axle. The above torque balance relationship is used to determine the second target axle suspension displacement S1 and the first target axle suspension displacement S2 required to maintain vehicle body attitude stability under the conditions of applying customized power and load transfer.

[0158] In one possible implementation, by adjusting the vertical stiffness of the second target axle suspension, it is possible to avoid sudden vehicle jerking that could cause passenger discomfort during brake force distribution switching.

[0159] It should be noted that the adjustment of the vertical stiffness of the second target axle suspension can be achieved by controlling the actuators of the electronically controlled suspension. The suspension torque balance relationship is used to calculate the amount of suspension displacement required to maintain vehicle body stability under customized power and load transfer conditions.

[0160] The processes described in S601-S603 above suppress vehicle pitch by adjusting the vertical stiffness of the second target axle suspension during brake force distribution switching, thus ensuring braking comfort during the switching process.

[0161] like Figure 7 The diagram shown is a seventh flowchart of a vehicle control method provided in an embodiment of this application, which includes the following steps.

[0162] S701: Acquire the second target axle suspension displacement signal and the first target axle suspension displacement signal of the vehicle.

[0163] The second target axle suspension displacement signal represents the displacement of the second target axle suspension, and the first target axle suspension displacement signal represents the displacement of the first target axle suspension.

[0164] In some examples, the suspension displacement of the first target axle can be obtained using a suspension height sensor.

[0165] It should be noted that the suspension displacement signals of the second target axle and the first target axle can be used to determine the attitude change of the vehicle body relative to the front first target axle, and then to determine the pitch state of the vehicle body.

[0166] S702: Determine the vehicle's body pitch state based on the second target axle suspension displacement signal and the first target axle suspension displacement signal.

[0167] Among them, the vehicle body pitch state represents the rotation state of the vehicle body about the lateral axis.

[0168] In some examples, the compression or extension of the front first target axle suspension can be determined based on the second target axle suspension displacement signal and the first target axle suspension displacement signal, thereby determining the vehicle's body pitch state.

[0169] In one possible implementation, the vehicle body exhibits a jerking state when the second target axle suspension extends and the first target axle suspension compresses.

[0170] It should be noted that the vehicle's pitch state refers to the rotational state of the vehicle body around the lateral axis (i.e., the axis in the left-right direction of the vehicle), including two typical states: nodding (i.e., pitching forward) and pitching (i.e., pitching backward). When the second target axle suspension compresses and the first target axle suspension extends, the vehicle body exhibits a pitching state; when the second target axle suspension extends and the first target axle suspension compresses, the vehicle body exhibits a jerking state.

[0171] S703: Based on the vehicle's pitch state, control the movement of the second target axle suspension actuator and the first target axle suspension actuator to reduce the vehicle's pitch.

[0172] Specifically, the vehicle body pitch is actively adjusted by controlling the actions of the second target axle suspension actuator and the first target axle suspension actuator.

[0173] In some examples, the second target axle suspension actuator and the first target axle suspension actuator are actuators of an electronically controlled suspension system that can actively adjust the vertical stiffness and damping of the suspension.

[0174] In one possible implementation, when it is determined that the vehicle is in a jerking state, the second target axle suspension actuator and the first target axle suspension actuator are controlled to operate, providing a force to resist vehicle body pitch, thereby reducing vehicle body pitch.

[0175] It should be noted that the second target axle suspension actuator and the first target axle suspension actuator can be actuators of electronically controlled suspension, such as solenoid valves, motors, etc., which can actively adjust the stiffness and damping of the suspension, thereby actively controlling the pitch of the vehicle body.

[0176] The process described in S701-S703 above, when the first target axle independently bears the braking force of the whole vehicle, determines the vehicle pitch state by acquiring the suspension displacement signal of the front first target axle, and controls the suspension actuator to move accordingly, further reducing the vehicle pitch and improving braking comfort.

[0177] like Figure 8 The diagram shown is an eighth flowchart of a vehicle control method provided in an embodiment of this application, which includes the following steps.

[0178] S801: Obtain the vehicle's suspension stiffness parameters and suspension displacement signals.

[0179] Among them, the suspension stiffness parameter characterizes the vertical stiffness of the suspension system, and the suspension displacement signal characterizes the displacement of the suspension.

[0180] In some examples, suspension stiffness parameters can be obtained from signals from sensors inside the electronically controlled suspension, while suspension displacement signals can be obtained from suspension height sensors.

[0181] It should be noted that the suspension stiffness parameters may include the vertical stiffness of the second target axle suspension and the vertical stiffness of the first target axle suspension, and the suspension displacement signals may include the suspension displacement signals of the second target axle suspension and the first target axle suspension. The suspension stiffness parameters and suspension displacement signals are used to calculate the real-time load on the first target axle.

[0182] S802: Determine the real-time load of the vehicle's first target axle based on the suspension stiffness parameters and suspension displacement signals.

[0183] Among them, the real-time load of the first target shaft is the real-time vertical load on the first target bearing during the braking process.

[0184] In some examples, the real-time load F on the first target axis rear =C2×S2, where C2 is the vertical stiffness of the suspension on the first target axle, and S2 is the displacement of the suspension on the first target axle. During braking, the load on the first target axle will change due to inertial transfer, therefore the load on the first target axle needs to be determined in real time.

[0185] In one possible implementation, the real-time load on the first target axle can be calculated in real time based on the suspension stiffness parameters and the suspension displacement signal.

[0186] It should be noted that the real-time load on the first target axle refers to the real-time vertical load on the first target bearing during braking, which varies with braking deceleration and load transfer. By determining the real-time load on the first target axle, the upper limit of the braking force on the first target axle can be calculated more accurately.

[0187] S803: Update the upper limit of braking force of the first target axle based on the real-time load of the first target axle and the road surface adhesion parameters.

[0188] The upper limit of the braking force of the first target axle is updated based on the real-time load of the first target axle and the road surface adhesion parameters.

[0189] In some examples, the upper limit of the braking force on the first target axle is calculated as: real-time load on the first target axle × road surface adhesion parameter × preset coefficient. As the real-time load on the first target axle changes during braking, the upper limit of the braking force on the first target axle is updated accordingly.

[0190] In one possible implementation, by updating the upper limit of the braking force of the first target axis in real time, it can be ensured that the first target axis priority strategy is always executed based on the actual attachment conditions, thereby improving the accuracy and safety of braking force distribution.

[0191] It should be noted that updating the upper limit of the first target axle braking force means recalculating the upper limit of the first target axle braking force based on the real-time load change of the first target axle during braking, so as to ensure that the braking force of the first target axle never exceeds the maximum braking force that the first target axle can output under the current adhesion conditions.

[0192] The processes described in S801-S803 above, by determining the real-time load of the first target axis and updating the upper limit of the braking force of the first target axis in real time, enable the first target axis priority strategy to adapt to the dynamic changes of the load during braking, thereby further improving the accuracy and safety of braking force distribution.

[0193] In specific implementation scenarios, the vehicle control method of this application embodiment may include the following processes:

[0194] The vehicle is traveling at a moderate speed on a dry asphalt road surface. The driver applies the brake pedal for non-emergency braking. The electronic brake pedal collects the driver's braking demand and transmits it to the central domain controller, which determines the target braking force for the entire vehicle. Simultaneously, the suspension displacement signals of the second and first target axles are acquired via suspension height sensors. Combined with the vertical stiffness of the second and first target axles, the load on the first target axle is determined. The vehicle's intelligent driving camera identifies the current road surface as asphalt, and the road adhesion parameters are determined based on the system database. The adhesion limit of the first target axle is determined based on the first target axle load and the road adhesion parameters. The product of the first target axle's adhesion limit and a preset coefficient is used to determine the upper limit of the braking force for the first target axle.

[0195] When the target braking force of the entire vehicle is less than or equal to the upper limit of the braking force of the first target axle, the braking force of the first target axle is controlled to be equal to the target braking force of the entire vehicle, and the braking force of the second target axle is zero. At this time, the entire braking force of the vehicle is borne by the first target axle, the load transfer of the second target axle is reduced, and the additional impact of the second target axle braking force on the vehicle pitch is reduced. At the same time, the vehicle pitch state is determined based on the suspension displacement signals of the second target axle and the first target axle. If the vehicle body shows a jerking trend, the suspension actuators of the second target axle and the first target axle are controlled to operate to suppress vehicle jerking.

[0196] When the driver continues to depress the brake pedal, increasing the target braking force of the vehicle to a level greater than the upper limit of the first target axle braking force, the first target axle braking force is controlled to remain at the upper limit of the first target axle braking force, and the second target axle braking force is controlled to increase, so that the sum of the second target axle braking force and the first target axle braking force equals the target braking force of the vehicle, thereby preventing the first target axle from locking up while ensuring that the braking performance of the vehicle is not reduced.

[0197] If, during a single braking operation, the vehicle transitions from a dry asphalt road surface to an icy or snowy road surface, causing the road adhesion parameter to be less than or equal to a preset adhesion parameter threshold, or if the driver performs an emergency braking operation causing the braking urgency level to be greater than or equal to a preset urgency level threshold, then the vehicle is determined to switch from the first operating condition to the second operating condition. At this time, the target braking force of the second target axle and the target braking force of the first target axle are determined based on the ideal I curve, and the braking force of the second target axle is controlled to be equal to the target braking force of the second target axle, and the braking force of the first target axle is controlled to be equal to the target braking force of the first target axle. Simultaneously, the vertical stiffness of the second target axle suspension is acquired, and the target stiffness of the second target axle suspension is determined based on the target braking force of the second target axle. The vertical stiffness of the second target axle suspension is then adjusted to the target stiffness of the second target axle suspension to suppress vehicle pitch during the braking force distribution switch. Only one switch is allowed during a single braking operation, and the vehicle will not revert to the first operating condition after the switch, avoiding repeated strategy switching that could affect ride comfort.

[0198] If the real-time load of the first target axle changes during braking, the real-time load of the first target axle is determined based on the suspension stiffness parameters and suspension displacement signals, and the upper limit of the braking force of the first target axle is updated based on the real-time load of the first target axle and the road surface adhesion parameters to ensure that the first target axle priority strategy is always executed based on the actual adhesion conditions.

[0199] Through the above process, the vehicle control method of this application embodiment can prioritize the braking force of the whole vehicle by the first target axle under non-emergency braking conditions, reduce the additional impact of the braking force of the second target axle on the vehicle pitch, and improve braking comfort; when the first target axle is insufficient, the second target axle supplements the braking force to ensure braking performance; switch to ideal I curve distribution under low-adhesion or emergency braking conditions to ensure braking safety; and further improve ride comfort through suspension coordination and unidirectional switching logic.

[0200] like Figure 10 The diagram shown is a schematic representation of a vehicle architecture according to an embodiment of this application. The vehicle includes a processor 1001, a memory 1002, and a bus 1003. The processor 1001 and the memory 1002 are connected via the bus 1003. The memory 1002 is used to store programs, and the processor 1001 is used to run the programs. When the programs run, they execute the vehicle control method provided in the above embodiment, including the following steps:

[0201] Obtain the vehicle's overall target braking force and the upper limit of the first target axle braking force;

[0202] When the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be equal to the target braking force of the whole vehicle.

[0203] When the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be maintained at the upper limit of the first target axle braking force, and the second target axle braking force of the vehicle is controlled so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle.

[0204] Optionally, obtaining the upper limit of the braking force of the first target axle includes:

[0205] Obtain the first target axle load of the vehicle and the road surface adhesion parameters of the current driving surface;

[0206] Based on the first target axle load and the road surface adhesion parameters, the upper limit of the first target axle braking force is determined.

[0207] Optionally, the first target axle load of the vehicle and the road adhesion parameters of the current driving surface are obtained, including:

[0208] The suspension sensors of the vehicle are used to acquire the suspension displacement signals of the second target axle and the first target axle.

[0209] The first target axle load of the vehicle is determined based on the second target axle suspension displacement signal and the first target axle suspension displacement signal;

[0210] The vehicle's environmental perception device obtains information about the type of the current road surface.

[0211] Based on the type information, determine the road surface adhesion parameters of the current driving surface.

[0212] Optionally, based on the first target axle load and the road surface adhesion parameters, the upper limit of the first target axle braking force is determined, including:

[0213] The adhesion limit of the first target axle is determined based on the first target axle load and the road surface adhesion parameters.

[0214] The product of the adhesion limit of the first target axis and a preset coefficient is determined as the upper limit of the braking force of the first target axis; the preset coefficient is less than 1.

[0215] Optionally, before controlling the first target axle braking force of the vehicle to equal the target braking force of the vehicle when the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the method further includes:

[0216] The braking urgency of the vehicle and the road surface adhesion parameters of the current driving surface are obtained.

[0217] When the road surface adhesion parameter is greater than a preset adhesion parameter threshold and the braking urgency is less than a preset urgency threshold, the vehicle is determined to be in the first operating condition.

[0218] When the road surface adhesion parameter is less than or equal to the preset adhesion parameter threshold or the braking emergency level is greater than or equal to the preset emergency level threshold, the vehicle is determined to be in the second operating condition.

[0219] When the vehicle is in the first operating condition, the following steps are performed: when the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be equal to the target braking force of the whole vehicle; when the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be maintained at the upper limit of the first target axle braking force, and the second target axle braking force of the vehicle is controlled so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle.

[0220] When the vehicle is in the second operating condition, the target braking force of the second target axle and the target braking force of the first target axle of the vehicle are determined according to the preset front and rear braking force distribution curve, and the target braking force of the second target axle of the vehicle is controlled to be equal to the target braking force of the second target axle and the target braking force of the first target axle of the vehicle is controlled to be equal to the target braking force of the first target axle.

[0221] Optionally, the method further includes:

[0222] When the vehicle is in the first operating condition, when the vehicle switches from the first operating condition to the second operating condition during a single braking process, the second target axle target braking force and the first target axle target braking force of the vehicle are determined according to the preset front and rear braking force distribution curve. The second target axle braking force of the vehicle is controlled to be equal to the second target axle target braking force and the first target axle braking force of the vehicle is equal to the first target axle target braking force. During the single braking process, the second target axle braking force is kept equal to the second target axle target braking force and the first target axle braking force of the vehicle is kept equal to the first target axle target braking force.

[0223] Optionally, when determining the target braking force of the second target axle and the target braking force of the first target axle of the vehicle based on the preset front and rear braking force distribution curve, the method further includes:

[0224] Obtain the vertical stiffness of the second target axle suspension of the vehicle;

[0225] The target stiffness of the second target axle suspension of the vehicle is determined based on the target braking force of the second target axle;

[0226] The second target axle suspension of the vehicle is controlled to adjust from the vertical stiffness of the second target axle suspension to the target stiffness of the second target axle suspension in order to suppress the vehicle body pitch when the braking force distribution is switched.

[0227] Optionally, when controlling the first target axle braking force of the vehicle to be equal to the overall vehicle target braking force, the method further includes:

[0228] Acquire the second target axle suspension displacement signal and the first target axle suspension displacement signal of the vehicle;

[0229] The vehicle body pitch state is determined based on the second target axle suspension displacement signal and the first target axle suspension displacement signal;

[0230] Based on the vehicle body pitch state, the second target axle suspension actuator and the first target axle suspension actuator of the vehicle are controlled to operate, so as to reduce the vehicle body pitch.

[0231] Optionally, the method further includes:

[0232] Obtain the suspension stiffness parameters and suspension displacement signals of the vehicle;

[0233] The real-time load of the first target axle of the vehicle is determined based on the suspension stiffness parameters and the suspension displacement signal.

[0234] The upper limit of braking force of the first target axle is updated based on the real-time load of the first target axle and the road surface adhesion parameters.

[0235] In summary, this application compares the target braking force of the entire vehicle with the upper limit of the braking force of the first target axle. Within the capacity of the first target axle, the first target axle independently bears the braking force, reducing the load transfer of the second target axle and minimizing the additional impact of the second target axle's braking force on vehicle pitch. When the braking force exceeds the capacity of the first target axle, the second target axle supplements, ensuring that braking performance is not reduced. The upper limit of the braking force of the first target axle is determined based on the first target axle load and road surface adhesion parameters and multiplied by a preset coefficient less than 1, providing safety redundancy and preventing the first target axle from locking up. Operating conditions are divided based on the urgency of braking and road surface adhesion parameters. During low-adhesion or emergency braking, the braking force is distributed according to a preset curve to ensure braking safety. Only one switching is allowed in a single braking operation to avoid repeated switching, and the suspension stiffness of the second target axle is adjusted during switching to suppress vehicle pitch. During the priority phase of the first target axle, vehicle pitch is further reduced through suspension actuators. Simultaneously, the load of the first target axle and the upper limit of the braking force are updated in real time based on suspension stiffness and displacement signals to adapt to load changes during braking. Thus, while ensuring braking performance, braking comfort and safety are comprehensively improved.

[0236] While several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this application. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0237] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A vehicle control method, characterized in that, include: Obtain the vehicle's overall target braking force and the upper limit of the first target axle braking force; When the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be equal to the target braking force of the whole vehicle. When the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be maintained at the upper limit of the first target axle braking force, and the second target axle braking force of the vehicle is controlled so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle.

2. The method according to claim 1, characterized in that, Obtaining the upper limit of the braking force of the first target shaft includes: Obtain the first target axle load of the vehicle and the road surface adhesion parameters of the current driving surface; Based on the first target axle load and the road surface adhesion parameters, the upper limit of the first target axle braking force is determined.

3. The method according to claim 2, characterized in that, Obtaining the first target axle load of the vehicle and the road adhesion parameters of the current driving surface includes: The suspension sensors of the vehicle are used to acquire the suspension displacement signals of the second target axle and the first target axle. The first target axle load of the vehicle is determined based on the second target axle suspension displacement signal and the first target axle suspension displacement signal; The vehicle's environmental perception device obtains information about the type of the current road surface. Based on the type information, determine the road surface adhesion parameters of the current driving surface.

4. The method according to claim 2, characterized in that, Based on the first target axle load and the road surface adhesion parameters, the upper limit of the first target axle braking force is determined, including: The adhesion limit of the first target axle is determined based on the first target axle load and the road surface adhesion parameters. The product of the adhesion limit of the first target axis and a preset coefficient is determined as the upper limit of the braking force of the first target axis; the preset coefficient is less than 1.

5. The method according to claim 1, characterized in that, Before controlling the first target axle braking force of the vehicle to equal the target braking force of the vehicle when the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the method further includes: The braking urgency of the vehicle and the road surface adhesion parameters of the current driving surface are obtained. When the road surface adhesion parameter is greater than a preset adhesion parameter threshold and the braking urgency is less than a preset urgency threshold, the vehicle is determined to be in the first operating condition. When the road surface adhesion parameter is less than or equal to the preset adhesion parameter threshold or the braking emergency level is greater than or equal to the preset emergency level threshold, the vehicle is determined to be in the second operating condition. When the vehicle is in the first operating condition, the following steps are performed: when the target braking force of the whole vehicle is less than or equal to the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be equal to the target braking force of the whole vehicle; when the target braking force of the whole vehicle is greater than the upper limit of the first target axle braking force, the first target axle braking force of the vehicle is controlled to be maintained at the upper limit of the first target axle braking force, and the second target axle braking force of the vehicle is controlled so that the sum of the second target axle braking force and the first target axle braking force is equal to the target braking force of the whole vehicle. When the vehicle is in the second operating condition, the target braking force of the second target axle and the target braking force of the first target axle of the vehicle are determined according to the preset front and rear braking force distribution curve, and the target braking force of the second target axle of the vehicle is controlled to be equal to the target braking force of the second target axle and the target braking force of the first target axle of the vehicle is controlled to be equal to the target braking force of the first target axle.

6. The method according to claim 5, characterized in that, The method further includes: When the vehicle is in the first operating condition, when the vehicle switches from the first operating condition to the second operating condition during a single braking process, the second target axle target braking force and the first target axle target braking force of the vehicle are determined according to the preset front and rear braking force distribution curve. The second target axle braking force of the vehicle is controlled to be equal to the second target axle target braking force and the first target axle braking force of the vehicle is equal to the first target axle target braking force. During the single braking process, the second target axle braking force is kept equal to the second target axle target braking force and the first target axle braking force of the vehicle is kept equal to the first target axle target braking force.

7. The method according to claim 6, characterized in that, When determining the target braking force of the second target axle and the target braking force of the first target axle of the vehicle based on the preset front and rear braking force distribution curve, the method further includes: Obtain the vertical stiffness of the second target axle suspension of the vehicle; The target stiffness of the second target axle suspension of the vehicle is determined based on the target braking force of the second target axle; The second target axle suspension of the vehicle is controlled to adjust from the vertical stiffness of the second target axle suspension to the target stiffness of the second target axle suspension in order to suppress the vehicle body pitch when the braking force distribution is switched.

8. The method according to claim 1, characterized in that, When controlling the first target axle braking force of the vehicle to be equal to the overall vehicle target braking force, the method further includes: Acquire the second target axle suspension displacement signal and the first target axle suspension displacement signal of the vehicle; The vehicle body pitch state is determined based on the second target axle suspension displacement signal and the first target axle suspension displacement signal; Based on the vehicle body pitch state, the second target axle suspension actuator and the first target axle suspension actuator of the vehicle are controlled to operate, so as to reduce the vehicle body pitch.

9. The method according to claim 2, characterized in that, The method further includes: Obtain the suspension stiffness parameters and suspension displacement signals of the vehicle; The real-time load of the first target axle of the vehicle is determined based on the suspension stiffness parameters and the suspension displacement signal. The upper limit of braking force of the first target axle is updated based on the real-time load of the first target axle and the road surface adhesion parameters.

10. A vehicle, characterized in that, include: Processor, memory, and bus; The processor and the memory are connected via the bus; The memory is used to store a program, and the processor is used to run the program, wherein the program is executed by the processor to perform the vehicle control method according to any one of claims 1 to 9.

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