Vehicle control method, electronic equipment, vehicle and storage medium

Abstract

The invention provides a vehicle control method, electronic equipment, a vehicle and a storage medium, the method is applied to the vehicle control technology, and the method comprises the steps that in the vehicle driving process, the wheel speed of each wheel of the vehicle and the current vehicle speed of the vehicle are obtained; according to the wheel speed of each wheel and the current vehicle speed, whether the vehicle is in a wheel speed abnormal working condition or not is judged; and under the condition that the vehicle is in the wheel speed abnormal working condition, if a mode switching request for entering a 4H mode is received, switching to the 4H mode is forbidden. According to the method, damage to mechanical parts of the transmission system caused by entering the 4H mode by mistake can be avoided, and the driving safety is improved.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and more specifically, to a vehicle control method, electronic device, vehicle, and storage medium within the field of vehicle control technology. Background Technology

[0002] Currently, to meet off-road driving needs, many vehicle models are equipped with part-time four-wheel drive systems. The core component of this part-time four-wheel drive system is a transfer case with a central mechanical locking mechanism. This transfer case can provide the driver with the following driving modes: high-speed two-wheel drive (2H) mode, high-speed four-wheel drive (4H) mode, and low-speed four-wheel drive (4L) mode, etc.

[0003] When the transfer case locks the front and rear axles in 4H mode, if there is a wheel speed difference between the front and rear axles, this wheel speed difference will be jammed by the mechanical locking fork in the central mechanical locking mechanism. This is converted into continuous alternating stress and friction within the transmission system, which may cause the mechanical locking fork or engagement sleeve of the transfer case to become stuck, preventing the driver from disengaging the transfer case from 4H mode. The vehicle will be forced to remain in 4H mode, and the abnormal stress and frictional heat within the transmission system will continue to accumulate, easily causing damage to mechanical components within the transmission system (such as the transfer case, drive shaft, differential, and other critical components), reducing the service life and reliability of the transmission system. Summary of the Invention

[0004] This application provides a vehicle control method, electronic device, vehicle, and storage medium. The method can prevent damage to mechanical components of the transmission system caused by accidentally entering 4H mode and improve driving safety.

[0005] Firstly, a vehicle control method is provided, the method comprising: during vehicle operation, acquiring the wheel speeds of each wheel of the vehicle and the current vehicle speed; determining whether the vehicle is in an abnormal wheel speed condition based on the wheel speeds of each wheel and the current vehicle speed; and if a mode switching request to enter 4H mode is received when the vehicle is in the abnormal wheel speed condition, then prohibiting switching to 4H mode.

[0006] The aforementioned technical solution, by acquiring the wheel speeds of each wheel and the current vehicle speed, can proactively and objectively identify whether the vehicle is in an abnormal wheel speed condition caused by inconsistent wheel parameters. This process does not rely on the driver's subjective experience or observation, providing a decision-making basis for subsequent protective actions. Furthermore, by combining the analysis with the current vehicle speed, it ensures that the judgment of abnormal wheel speed conditions can be effectively and accurately executed across the entire vehicle's speed range, from low to high speeds. Upon identifying an abnormal wheel speed condition, if a mode switching request to enter 4H mode is received from the driver, switching to 4H mode will be prohibited, fundamentally preventing the possibility of rigidly locking the front and rear axles. Even if the driver attempts to use 4H mode under abnormal wheel speed conditions due to inexperience or negligence, the mode switching request can be promptly blocked. Therefore, prohibiting entry into 4H mode under abnormal wheel speed conditions effectively prevents a series of chain problems such as transfer case jamming and inability to exit 4H mode, and continuous abnormal stress damage to the transmission system, improving the intelligence, safety, and transmission system lifespan of part-time four-wheel drive vehicles.

[0007] In conjunction with the first aspect, in some possible implementations, determining whether the vehicle is in an abnormal wheel speed condition based on the wheel speeds of each wheel and the current vehicle speed includes: when the current vehicle speed is less than or equal to a preset vehicle speed threshold, determining the speed difference between the auxiliary drive shaft and the main drive shaft based on the wheel speeds of each wheel, and determining whether the vehicle is in an abnormal wheel speed condition based on the speed difference; when the current vehicle speed is greater than the preset vehicle speed threshold, determining the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the wheel speeds of each wheel, and determining whether the vehicle is in an abnormal wheel speed condition based on the degree of slippage; wherein, one of the auxiliary drive shaft and the main drive shaft is the front axle and the other is the rear axle.

[0008] The aforementioned technical solution employs different judgment methods for abnormal wheel speed conditions based on varying vehicle speed ranges. It combines the sensitivity advantage of inter-axle speed difference at low speeds with the stability and adaptability advantage of relative slippage at high speeds, ensuring high reliability and accuracy in monitoring abnormal wheel speed conditions across the entire speed range, from extremely low to maximum speeds. This refined judgment across different speed segments allows for more accurate identification of abnormal wheel speed conditions, enabling intervention in 4H mode only when necessary. This ensures safety while maximizing driver freedom of operation under normal conditions.

[0009] In conjunction with the first aspect and the above implementation, in some possible implementations, each wheel includes: a first wheel and a second wheel at both ends of the auxiliary drive shaft, and a third wheel and a fourth wheel at both ends of the main drive shaft; determining the speed difference between the auxiliary drive shaft and the main drive shaft based on the wheel speeds of each wheel includes: determining the axle speed of the auxiliary drive shaft based on the wheel speeds of the first wheel and the second wheel; determining the axle speed of the main drive shaft based on the wheel speeds of the third wheel and the fourth wheel; determining the speed difference between the auxiliary drive shaft and the main drive shaft based on the axle speeds of the auxiliary drive shaft and the main drive shaft; or, determining the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the wheel speeds of each wheel includes: determining the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the speed difference between the auxiliary drive shaft and the main drive shaft and the axle speed of the main drive shaft.

[0010] In combination with the first aspect and the above implementation methods, in some possible implementation methods, determining whether the vehicle is in an abnormal wheel speed condition based on the speed difference includes: determining that the vehicle is in an abnormal wheel speed condition when the absolute value of the speed difference is greater than a preset speed difference threshold for a duration exceeding a first preset duration; and determining that the vehicle is not in an abnormal wheel speed condition when the absolute value of the speed difference is greater than the preset speed difference threshold for a duration not exceeding the first preset duration, or when the absolute value of the wheel speed difference is less than or equal to the preset speed difference threshold.

[0011] The aforementioned technical solution introduces a dual judgment mechanism combining a preset speed difference threshold and a first preset duration when the vehicle speed is low. The preset speed difference threshold defines abnormal speed differences, which helps filter out a large number of normal, minor fluctuations. The first preset duration confirms the persistence of the anomaly from a time perspective, effectively filtering out various instantaneous and occasional interference signals. Together, these two mechanisms identify persistent inter-axle speed differences that exceed the normal allowable range, improving the accuracy and reliability of identifying abnormal wheel speed conditions. This ensures that subsequent decisions to intervene in the 4H mode switching are both timely and accurate, minimizing the impact of misjudgments on the driver's operation under normal conditions.

[0012] In conjunction with the first aspect and the above implementation methods, in some possible implementation methods, determining whether the vehicle is in an abnormal wheel speed condition based on the degree of slip includes: determining that the vehicle is in an abnormal wheel speed condition when the absolute value of the slip degree is greater than a preset slip degree threshold for a duration exceeding a second preset duration; and determining that the vehicle is not in an abnormal wheel speed condition when the absolute value of the slip degree is greater than the preset slip degree threshold for a duration not exceeding the second preset duration, or when the absolute value of the slip degree is less than or equal to the preset slip degree threshold.

[0013] The aforementioned technical solution, when the current vehicle speed is high, introduces a dual judgment mechanism combining a preset slip degree threshold and a second preset duration. The preset slip degree threshold defines the abnormal slip degree, which helps filter out a large amount of normal slip. The second preset duration confirms the persistence of the anomaly from a time dimension, effectively filtering out various instantaneous and occasional interference signals. Together, these two mechanisms identify persistent inter-axle slip that exceeds the normal allowable range, improving the accuracy and reliability of identifying abnormal wheel speed conditions. This ensures that subsequent decisions to intervene in 4H mode switching are both timely and accurate, minimizing the impact of misjudgments on the driver's operation under normal conditions.

[0014] In combination with the first aspect and the above implementation methods, in some possible implementation methods, if a mode switching request to enter 4H mode is received when the vehicle is in the abnormal wheel speed condition, the method further includes: outputting a prompt message to inform the driver of the reason why entering 4H mode is prohibited.

[0015] The above technical solution, when the vehicle is in an abnormal wheel speed condition, if it receives a mode switching request to enter 4H mode, in addition to executing the core safety instruction to prohibit switching, outputs prompt information to ensure that the driver clearly understands the reason for the restriction of operation, thereby improving the transparency of human-computer interaction and driving experience.

[0016] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the step of prohibiting switching to the 4H mode if a mode switching request to enter the 4H mode is received includes: if a mode switching request to enter the 4H mode is received, the current mode switching state is set from the valid state to the invalid state to prohibit switching to the 4H mode.

[0017] The above technical solution, by switching the internal mode state, requires no addition or modification to the hardware circuit, resulting in low cost and high reliability. The state setting operation is an internal logic operation of the controller, with a fast response speed, ensuring immediate protection upon identification of abnormal wheel speed conditions. Under abnormal wheel speed conditions, if a mode switching request to enter 4H mode is received, the dangerous mode switching operation can be prohibited at the logic level.

[0018] In summary, the above technical solution monitors the wheel speeds of each wheel and the current vehicle speed in real time during vehicle operation. Based on the vehicle speed, it intelligently selects between axle speed differences or relative slippage as the judgment criteria to actively identify abnormal wheel speed conditions caused by inconsistent tire physical parameters across the entire vehicle speed range. When such an abnormal condition is detected, it intervenes in the driver's mode switching request, prohibiting the transfer case from switching to the 4H mode, which rigidly locks the front and rear axles. This solution effectively solves the inherent defects of related technologies that rely entirely on driver experience and where misuse of the 4H mode can easily lead to the transfer case locking mechanism jamming and subsequent abnormal stress damage to the transmission system. By prohibiting entry into the 4H mode, mechanical failures are avoided at the source, improving the safety, intelligence, and transmission system reliability of part-time four-wheel drive vehicles. Furthermore, by outputting prompts, it ensures that the driver clearly understands the reason for the mode switching operation restriction, improving the transparency of human-machine interaction and driving experience, and avoiding driver confusion.

[0019] Secondly, a vehicle control device is provided, comprising: an acquisition module for acquiring the wheel speeds of each wheel of the vehicle and the current vehicle speed during vehicle operation; a judgment module for determining whether the vehicle is in an abnormal wheel speed condition based on the wheel speeds of each wheel and the current vehicle speed; and a prohibition module for prohibiting switching to the 4H mode if a mode switching request to enter the 4H mode is received when the vehicle is in the abnormal wheel speed condition.

[0020] Thirdly, an electronic device is provided, comprising: a memory for storing executable program code; and a processor for calling and running the executable program code from the memory, causing the vehicle to perform the method described in the first aspect or any possible implementation thereof.

[0021] Fourthly, a vehicle is provided that includes the electronic equipment described in the third aspect above.

[0022] Fifthly, a computer program product is provided, comprising: computer program code, which, when run on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof.

[0023] In a sixth aspect, a non-volatile storage medium is provided, which stores computer program code that, when executed on a computer, causes the computer to perform the method described in the first aspect or any possible implementation thereof. Attached Figure Description

[0024] Figure 1This is a vehicle architecture diagram provided in an embodiment of this application; Figure 2 This is a schematic flowchart of a vehicle control method provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a vehicle control device provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0025] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0026] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0027] Currently, many vehicle models are equipped with part-time four-wheel drive systems to meet off-road driving needs. The core component of this system is the transfer case with a central mechanical locking mechanism. This transfer case offers the driver the following driving modes: high-speed two-wheel drive (2H), high-speed four-wheel drive (4H), low-speed four-wheel drive (4L), all-wheel drive (AWD), and energy recovery mode. In 4H and 4L modes, the transfer case can rigidly lock the front and rear axles, ensuring a 1:1 torque distribution from the transmission to the front and rear axles, significantly improving off-road performance. In lightly complex terrains such as sandy roads, gravel beaches, and muddy country roads, 4H mode maintains drive force output without significantly reducing vehicle speed. 4L mode provides greater wheel-end torque for extreme conditions such as climbing steep slopes and getting out of difficult situations. The mechanical locking structure of the transfer case is simple and reliable, and the power transmission is direct and efficient, making it widely used in vehicles emphasizing off-road performance.

[0028] Although the aforementioned part-time four-wheel drive system exhibits superior performance in off-road scenarios, this application has discovered, through research, that the control strategy of the part-time four-wheel drive system has the following problems during daily use: The mode switching in this technology relies on the driver's subjective judgment. If a driver mistakenly switches the vehicle to 4H mode on a paved road with good traction, the high road surface adhesion and the rigid locking of the front and rear axles prevent differential speed control. This means that the speed difference between the inner and outer wheels during cornering cannot be absorbed by the differential speed control, leading to steering braking within the transmission system. This may manifest as heavy steering and difficulty in steering, significantly increasing driving difficulty and potentially causing vehicle instability due to wheel slippage, even posing a rollover risk. This technology lacks any detection or warning mechanism for this, relying entirely on the driver's experience and attention, thus posing a risk of misusing 4H mode.

[0029] Furthermore, the safe use of this part-time four-wheel drive system relies on the consistency of tire model, brand, wear level, and tire pressure across the vehicle. This ensures that the wheel speeds of all wheels (especially those between the front and rear axles for comparison) are essentially the same, allowing for synchronized rotation of the front and rear axles when four-wheel drive is locked. However, in daily vehicle use, differences in tire brand, model, wear level, or tire pressure can lead to variations in the actual wheel speeds. When the transfer case locks the front and rear axles in 4H mode, if a wheel speed difference exists between the front and rear axles, this difference will be jammed by the mechanical locking fork in the central mechanical locking mechanism. This is countered by the rigid drivetrain, transforming into continuous alternating stress and friction within the transmission system. This can cause the mechanical locking fork or engagement sleeve of the transfer case to become stuck, preventing the driver from disengaging the transfer case from 4H mode. The vehicle will be forced to operate in 4H mode, and the abnormal stress and friction heat inside the transmission system will continue to accumulate, which can easily cause damage to mechanical parts (such as transfer case, drive shaft, differential and other key components) in the transmission system, reducing the service life and reliability of the transmission system.

[0030] In summary, the control strategy of part-time four-wheel drive systems relies on correct driver operation and ideal tire alignment, lacking the ability to perceive and judge the actual driving conditions of the vehicle. This results in an inability to provide effective driving safety protection when wheel speeds are abnormal, potentially leading to mechanical jamming, abnormal component wear, and even driving safety risks. Therefore, how to avoid damage to the transmission system's mechanical components caused by accidentally entering 4H mode and improve driving safety has become an urgent technical problem to be solved.

[0031] To at least address the aforementioned technical problems, this application provides a vehicle control method applied to a controller in the vehicle. This controller can be a transfer case controller or other controllers; this embodiment does not limit the specific controller. When the vehicle is in an abnormal wheel speed condition, if a mode switching request to enter 4H mode is received, the method prohibits switching to 4H mode. This avoids the vehicle being unable to exit 4H mode due to abnormal wheel speed, which could indirectly lead to damage to the transmission system and improve driving safety.

[0032] The vehicle in this application embodiment includes a transfer case, for example, such as Figure 1 As shown, Figure 1 This is a vehicle architecture diagram provided in an embodiment of this application.

[0033] For example, such as Figure 1 As shown, vehicle 100 includes: wheels, engine 105, transmission 106, transfer case 107, front final drive 108, rear final drive 109, first output shaft 110, and second output shaft 111. The wheels include: left front wheel 101, right front wheel 102, left rear wheel 103, and right rear wheel 104. The output shaft of engine 105 is connected to the input shaft of transmission 106, and the output shaft of transmission 106 is connected to the input shaft of transfer case 107.

[0034] The first output shaft 110 of the transfer case 107 is connected to the front final drive 108, and the second output shaft 111 of the transfer case 107 is connected to the rear final drive 109. The rear final drive 109 is connected to the left rear wheel 103 and the right rear wheel 104 via drive shafts. The front final drive 108 is connected to the left front wheel 101 and the right front wheel 102 via drive shafts. The vehicle's power is transmitted from the transfer case 107 to the front final drive 108 and the rear final drive 109, and distributed by the front final drive 108 to the left front wheel 101 and the right front wheel 102, and by the rear final drive 109 to the left rear wheel 103 and the right rear wheel 104.

[0035] It should be noted that, Figure 1 This is merely a schematic diagram of a vehicle architecture applicable to an embodiment of this application. In specific implementations, the control method provided in this application embodiment can also be applied to vehicles with other architectures, and is not limited here.

[0036] Figure 2 This is a schematic flowchart of a vehicle control method provided in an embodiment of this application.

[0037] For example, such as Figure 2 As shown, the control method includes the following steps 201 to 203: Step 201: During the vehicle's operation, obtain the wheel speed of each wheel and the vehicle's current speed.

[0038] Step 202: Determine whether the vehicle is in an abnormal wheel speed condition based on the wheel speed of each wheel and the current vehicle speed.

[0039] Step 203: If a mode switching request to enter 4H mode is received when the vehicle is in an abnormal wheel speed condition, then switching to 4H mode is prohibited.

[0040] The following is about Figure 2 The specific implementation methods of each step in the illustrated embodiment are explained below: In step 201, the wheel speed of each wheel refers to: such as Figure 1 The instantaneous angular velocity of each of the four wheels of the vehicle shown is typically measured by wheel speed sensors installed at the hub of each wheel, and is usually expressed in revolutions per minute (rpm) or radians per second (rad / s). The vehicle's current speed refers to its longitudinal speed, a physical quantity characterizing the vehicle's translational motion, and is usually expressed in kilometers per hour (km / h) or meters per second (m / s). Current speed can usually be calculated from the wheel speed and rolling radius. In other words, wheel speed and vehicle speed can be converted to each other.

[0041] During vehicle operation, the controller can collect wheel speed signals from all four wheels in real time via the vehicle's Controller Area Network (CAN) bus to obtain the wheel speed of each wheel and calculate the current vehicle speed. Alternatively, it can directly collect the current vehicle speed using vehicle speed sensors. The controller is set to a fixed sampling period (e.g., 10 milliseconds) to continuously monitor and read wheel speed signals, vehicle speed signals, etc., ensuring the real-time performance and continuity of the data.

[0042] In step 202, it is understood that during normal driving, the wheel speeds of the four wheels are usually not completely consistent and may have expected minor differences. This abnormal wheel speed condition refers to a condition in which there are unexpected differences in the wheel speeds of each wheel. It excludes normal, instantaneous dynamic differences, and specifically refers to an unexpected deviation in wheel speeds that exceeds the normal fluctuation range, caused by inconsistencies in the physical state of the tires themselves, under driving conditions that should be consistent.

[0043] The reason for identifying abnormal wheel speed conditions in this step is that, in 4H mode, the mechanical lock-up of the transfer case cannot tolerate wheel speed differences caused by variations in the physical state of the tires themselves. In the locked state, the front and rear axles are rigidly connected and forced to rotate synchronously. Any sustained wheel speed difference can be converted into parasitic power circulation within the drivetrain, leading to stress concentration, overheating, and damage to mechanical components. Identifying abnormal wheel speed conditions is essentially a safety diagnostic test to determine whether the current vehicle state is compatible with 4H mode; it diagnoses wheel speed differences that fundamentally conflict with the mechanical lock-up.

[0044] In some embodiments, to ensure that the vehicle can effectively and reliably identify abnormal wheel speed conditions across the entire speed range, this embodiment dynamically selects two different judgment logics based on a comparison between the current vehicle speed and a preset vehicle speed threshold. For the low-speed segment, a judgment method based on the speed difference is used, while for the high-speed segment, a judgment method based on the degree of relative slip is used. The preset vehicle speed threshold is a calibration value used to divide the high-speed and low-speed segments, typically set in a lower speed range (e.g., 20-40 km / h). Optionally, the preset vehicle speed threshold can be set to 30 km / h; however, this embodiment does not specifically limit this setting.

[0045] For example, based on the current vehicle speed, step 202 above includes the following two implementation methods: Implementation Method 1: When the current vehicle speed is less than or equal to a preset vehicle speed threshold, determine the speed difference between the auxiliary drive shaft and the main drive shaft based on the wheel speed of each wheel, and determine whether the vehicle is in an abnormal wheel speed condition based on the speed difference.

[0046] In this configuration, one of the auxiliary drive axle and the main drive axle is the front axle, and the other is the rear axle. The main drive axle is the axle that always receives power from the engine and transmission and drives the vehicle in 2H mode. The auxiliary drive axle is the axle that is only connected to the powertrain when the vehicle needs to switch to four-wheel drive mode (4H or 4L mode) via the transfer case operated by the driver. For a given vehicle, its main and auxiliary drive axles are determined during the design and manufacturing phases, primarily depending on the vehicle's powertrain layout. In practice, there are two possibilities: the rear axle is the main drive axle, and the front axle is the auxiliary drive axle; or, the front axle is the main drive axle, and the rear axle is the auxiliary drive axle.

[0047] If the current vehicle speed is less than or equal to a preset speed threshold, it indicates that the current speed is low. At low speeds, the vehicle's dynamics are relatively simple, and there are fewer interfering factors such as wheel slippage. In this case, the speed difference between the front and rear drive axles can be used directly as the basis for judgment, which is not only simple to calculate but also highly accurate.

[0048] Understandably, at lower vehicle speeds, the speed difference between the front and rear drive axles is relatively small. If relative slip is used for judgment, the calculated relative slip will be small regardless of whether abnormal wheel speed conditions occur. In other words, at lower vehicle speeds, the calculated relative slip will not differ significantly regardless of whether abnormal wheel speed conditions occur. Therefore, at lower vehicle speeds, relative slip may not accurately identify abnormal wheel speed conditions. Thus, at lower vehicle speeds, the speed difference between the front and rear drive axles can be directly used as the basis for judging abnormal wheel speed conditions.

[0049] In some embodiments, each wheel includes: a first wheel and a second wheel at both ends of the auxiliary drive shaft, and a third wheel and a fourth wheel at both ends of the main drive shaft. Determining the speed difference between the auxiliary drive shaft and the main drive shaft based on the wheel speeds of each wheel includes: determining the axle speed of the auxiliary drive shaft based on the wheel speeds of the first and second wheels; determining the axle speed of the main drive shaft based on the wheel speeds of the third and fourth wheels; and determining the speed difference between the auxiliary drive shaft and the main drive shaft based on the axle speeds of the auxiliary drive shaft and the main drive shaft.

[0050] For example, the axle speed of the auxiliary drive shaft can be the average wheel speed between the wheel speeds of the first and second wheels. The axle speed of the main drive shaft can be the average wheel speed between the wheel speeds of the third and fourth wheels. The speed difference between the auxiliary drive shaft and the main drive shaft can be the difference obtained by subtracting the axle speed of the auxiliary drive shaft from the axle speed of the main drive shaft.

[0051] like Figure 1 As shown, assuming the main drive shaft is the rear axle and the auxiliary drive shaft is the front axle, then the first and second wheels are the left front wheel 101 and right front wheel 102, respectively, and the third and fourth wheels are the left rear wheel 103 and right rear wheel 104, respectively. The wheel speed of the left front wheel 101 is denoted as FLWheelSpd, the wheel speed of the right front wheel 102 as FRWheelSpd, the wheel speed of the left rear wheel 103 as RLWheelSpd, and the wheel speed of the right rear wheel 104 as RRWheelSpd. The axle speed of the front axle is denoted as Vr, the axle speed of the rear axle as Vf, and the speed difference between the front and rear axles as Vd. Vd can be calculated using the following formula: Vd=Vr-Vf=(RLWheelSpd+RRWheelSpd) / 2-(FLWheelSpd+FRWheelSpd) / 2 In some embodiments, the axle speed of the front axle can be referred to as the front axle rotational speed, and the axle speed of the rear axle can be referred to as the rear axle rotational speed. When both the wheel speed signals of the front and rear axle wheels are available, the front axle rotational speed is determined based on the wheel speed signals of the front axle wheels, and the rear axle rotational speed is determined based on the wheel speed signals of the rear axle wheels. If there is a first target wheel on the front axle whose wheel speed signal is unavailable, the front axle rotational speed is estimated; and if there is a second target wheel on the rear axle whose wheel speed signal is unavailable, the rear axle rotational speed is estimated.

[0052] In this context, "available" means the wheel speed signal is not lost and is valid, while "unavailable" means the wheel speed signal is lost or invalid. If the wheel speed signal of a particular wheel is available, it indicates that the wheel speed carried by that signal is reliable and can be directly used for subsequent calculations of the front / rear axle speeds. If the wheel speed signal of a particular wheel is unavailable, it indicates that the wheel speed carried by that signal is unreliable and cannot be directly used for subsequent calculations of the front / rear axle speeds.

[0053] When the wheel speed signals of the front axle wheels are available, the front axle speed Vf is calculated based on the wheel speeds FLWheelSpd of the left front wheel and FRWheelSpd of the right front wheel carried by the wheel speed signals. The front axle speed Vf can be calculated using the following formula 1: Vf=(FLWheelSpd+FRWheelSpd) / 2Formula 1 When the wheel speed signals of the rear axle wheels are available, the rear axle speed Vr is calculated based on the wheel speeds RLWheelSpd of the left rear wheel and RRWheelSpd of the right rear wheel carried by the wheel speed signals. The rear axle speed Vr can be calculated using the following formula 2: Vr=(RLWheelSpd+RRWheelSpd) / 2Formula 2 The following section mainly introduces how to estimate the front axle speed or rear axle speed when the wheel speed signal is unavailable.

[0054] See Figure 1 ,exist Figure 1In the vehicle architecture shown, considering cost and engineering necessity, the first output shaft 110 and the second output shaft 111 of the transfer case 107 do not necessarily both have speed sensors. For front-wheel drive vehicles, a speed sensor is typically placed near the first output shaft 110, which is related to the front axle drive, so that the speed of the first output shaft 110 is available. For rear-wheel drive vehicles, a speed sensor is typically placed near the second output shaft 111, which is related to the rear axle drive, so that the speed of the second output shaft 111 is available. Of course, in specific implementations, it is also possible that speed sensors are placed near both the first output shaft 110 and the second output shaft 111, so that the speeds of both output shafts of the transfer case 107 are available. When the output shaft speed is available, it can be further divided into two cases: the output shaft speed signal is in an available state or an unavailable state. Based on this, in this embodiment of the application, different front axle speed / rear axle speed estimation logic is provided for whether the output shaft speed of the transfer case is available: estimation method 1 is applicable when the output shaft speed of the transfer case is available, and estimation method 2 is applicable when the output shaft speed of the transfer case is unavailable.

[0055] The following describes how to estimate the front axle speed based on estimation method 1 described above: In some embodiments, when there is a first target wheel in the front axle where the wheel speed signal is unavailable, estimating the front axle speed includes: when the speed signal of the first output shaft is available, acquiring the speed of the first output shaft, and estimating the front axle speed based on the speed of the first output shaft, the rolling radius of the front axle wheel, and the speed ratio of the front final drive.

[0056] The fact that the speed signal of the first output shaft is available not only indicates that the speed of the first output shaft is obtainable, but also that the speed signal is valid and can be directly used to estimate the front shaft speed.

[0057] Specifically, the number of the first target wheels may be one or two; that is, the first target wheels may include the left front wheel and / or the right front wheel. For example... Figure 1 As shown, when the rotational speed signal of the first output shaft 110 is available, regardless of whether the wheel speed signal of a single front axle wheel is unavailable or both front axle wheel speed signals are unavailable, the front axle rotational speed can be estimated based on the rotational speed of the first output shaft 110, the rolling radius of the front axle wheels, and the speed ratio of the front final drive 108. For example, in this case, the front axle rotational speed Vf can be estimated using the following formula 3: Vf=(n1·r1·2π) / i1Formula 3 Where n1 is the rotational speed of the first output shaft 110, r1 is the rolling radius of the front axle wheel, and i1 is the speed ratio of the front final drive 108. Optionally, the average rolling radius of the left and right front wheels can be used as r1. The ratio of the product of n1, r1, and 2π to i1 is the estimated front axle rotational speed.

[0058] The following describes how to estimate the rear axle speed based on the above estimation method 1: In some embodiments, when there is a second target wheel in the rear axle where the wheel speed signal is unavailable, estimating the rear axle speed includes: when the speed signal of the second output shaft is available, acquiring the speed of the second output shaft, and estimating the rear axle speed based on the speed of the second output shaft, the rolling radius of the rear axle wheel, and the speed ratio of the rear final drive.

[0059] The fact that the speed signal of the second output shaft is available not only indicates that the speed of the second output shaft is obtainable, but also that the speed signal is valid and can be directly used to estimate the speed of the rear shaft.

[0060] Specifically, the number of the second target wheels may be one or two; that is, the second target wheels may include the left rear wheel and / or the right rear wheel. For example... Figure 1 As shown, when the rotational speed signal of the second output shaft 111 is available, regardless of whether the wheel speed signal of one wheel on the rear axle is unavailable or both wheel speed signals on the rear axle are unavailable, the rear axle rotational speed can be estimated based on the rotational speed of the second output shaft 111, the rolling radius of the rear axle wheels, and the speed ratio of the rear main reducer 109. For example, in this case, the rear axle rotational speed Vr can be estimated using the following formula 4: Vr = (n²·r²·2π) / i² (Formula 4) Where n2 is the rotational speed of the second output shaft 111, r2 is the rolling radius of the rear axle wheel, and i2 is the speed ratio of the rear main reducer 109. Optionally, the average rolling radius of the left and right rear wheels can be used as r2. The product of n2, r2, and 2π, and the ratio of i2, is the estimated rear axle rotational speed.

[0061] In this embodiment, when the speed signal of the transfer case's output shaft is available, the front axle speed / rear axle speed is calculated in reverse based on the power transmission path using the inherent mechanical relationship of the vehicle's transmission system. When some wheel speed signals fail, it can provide a stable and reliable data source to accurately estimate the front axle speed / rear axle speed.

[0062] The following describes how to estimate the front axle speed based on estimation method 2 described above: In some embodiments, when there is a first target wheel in the front axle where the wheel speed signal is unavailable, the front axle speed is estimated, including the following steps S11 to S15: S11: If the speed signal of the first output shaft is unavailable, determine whether the number of the first target wheels is 1.

[0063] The fact that the speed signal of the first output shaft is unavailable indicates that the speed of the first output shaft is not available, or that although the speed of the first output shaft is available, it may be unavailable due to loss or invalidity and cannot be directly used to estimate the front shaft speed.

[0064] When the rotational speed of the first output shaft is unavailable, the system first determines whether the number of target wheels whose wheel speed signals on the front axle are unavailable is one. It is understood that the number of target wheels may be one or two, meaning the target wheels may include the left front wheel and / or the right front wheel. When the target wheel is either the left or right front wheel, the number of target wheels is one. This embodiment primarily handles the case where the signal from one side of the front axle is unavailable.

[0065] S12: When there is only one first target wheel, determine the current driving state of the vehicle and the wheel speed of the third target wheel whose wheel speed signal is available in the front axle wheels.

[0066] The vehicle's current driving state can be determined by whether it is traveling in a straight line or turning. For example, if the wheel angle is greater than or equal to a preset angle threshold, the current driving state is determined to be turning; if the wheel angle is less than the preset angle threshold, the current driving state is determined to be traveling in a straight line. The preset angle threshold can be pre-calibrated, for example, to approximately 3 degrees. This embodiment only uses wheel angle as an example to illustrate determining the vehicle's driving state. In actual implementations, other methods can be used to determine the vehicle's driving state, and this embodiment does not impose specific limitations on this.

[0067] If the first target wheel with an unavailable wheel speed signal on the front axle is the left front wheel, then the third target wheel is the right front wheel. If the first target wheel with an unavailable wheel speed signal on the front axle is the right front wheel, then the third target wheel is the left front wheel.

[0068] S13: When the vehicle is in a turning state, obtain the turning radius and wheel track of the vehicle, and estimate the wheel speed of the first target wheel based on the turning radius, wheel track and wheel speed of the third target wheel.

[0069] The turning radius of a vehicle refers to the distance between the vehicle's center of gravity and the steering center; it can also be called the center-of-gravity turning radius. Assuming the vehicle's center of gravity is located between the front and rear axles, the turning radius is the distance from this center location to the steering center. The turning radius R can be calculated using the following formula: R=L / 2(sinψ) Formula 5 Where L represents the vehicle wheelbase, i.e., the distance between the front and rear axles, and ψ represents the wheel steering angle, specifically the equivalent front wheel steering angle, which can be calculated from the steering wheel angle via the steering system transmission ratio. Formula 5 is derived based on the Ackermann steering model, assuming the vehicle's center of gravity is located between the front and rear axles. Based on the principle that the inner and outer wheels rotate at the same angular velocity around the same steering center when the vehicle turns, and that the ratio of the wheel speeds of the outer and inner wheels is the same as the ratio of their turning radii, the wheel speed of the first target wheel is estimated.

[0070] Assuming the first target wheel is the outer wheel and the third target wheel is the inner wheel, the wheel speed W1 of the first target wheel can be estimated using the following formula 6: W1 = W3·(R+d / 2) / (Rd / 2) (Formula 6) Where W3 is the wheel speed of the third target wheel whose wheel speed is known, and d represents the wheelbase of the vehicle, i.e., the distance between the left and right wheels on the same axle. R+d / 2 can be approximated as the turning radius of the outer wheel, and Rd / 2 can be approximated as the turning radius of the inner wheel.

[0071] Assuming the first target wheel is the inner wheel and the third target wheel is the outer wheel, the wheel speed W1 of the first target wheel can be estimated using the following formula 7: W1 = W3·(Rd / 2) / (R+d / 2) (Formula 7) S14: When the driving state is straight-line driving, determine that the wheel speed of the first target wheel is the same as the wheel speed of the third target wheel.

[0072] It is understandable that when driving in a straight line, the wheel speeds of the wheels on both sides are basically the same. Therefore, it can be determined that the wheel speed of the third target wheel is taken as the wheel speed of the first target wheel.

[0073] S15: Estimate the front axle speed based on the wheel speeds of the first and third target wheels.

[0074] Specifically, the average of the wheel speeds of the first target wheel and the third target wheel can be used as the estimated front axle speed.

[0075] The following describes how to estimate the rear axle speed based on estimation method 2 described above: In some embodiments, when there is a second target wheel in the rear axle where the wheel speed signal is unavailable, estimating the rear axle speed includes the following steps S21 to S25: S21: If the speed signal of the second output shaft is unavailable, determine whether the number of the second target wheels is 1.

[0076] The fact that the speed signal of the second output shaft is unavailable indicates that the speed of the second output shaft is not available, or that although the speed of the second output shaft is available, it may be unavailable due to loss or invalidity and cannot be directly used to estimate the speed of the rear shaft.

[0077] When the rotational speed of the second output shaft is unavailable, the system first determines whether the number of second target wheels whose wheel speed signals on the rear axle are unavailable is one. It can be understood that the second target wheel could be either the left or right rear wheel (one in number), or it could be two (two in number). This embodiment primarily addresses the case where the rear axle wheel signal fails on only one side.

[0078] S22: When there is only one second target wheel, determine the current driving state of the vehicle and the wheel speed of the fourth target wheel whose wheel speed signal is available in the rear axle wheels.

[0079] The method for determining the driving status can be found in the relevant description in S12 above, and will not be repeated here to avoid repetition.

[0080] If the second target wheel whose wheel speed signal is unavailable on the rear axle is the left rear wheel, then the fourth target wheel is the right rear wheel. If the second target wheel whose wheel speed signal is unavailable on the rear axle is the right rear wheel, then the fourth target wheel is the left rear wheel.

[0081] S23: When the vehicle is in a turning state, obtain the turning radius and wheel track of the vehicle, and estimate the wheel speed of the second target wheel based on the turning radius, wheel track and wheel speed of the fourth target wheel.

[0082] For details regarding the vehicle's turning radius and track width, please refer to section S13 above. To avoid repetition, these details will not be repeated here.

[0083] Assuming the second target wheel is the outer wheel and the fourth target wheel is the inner wheel, the wheel speed W2 of the second target wheel can be estimated using the following formula 8: W2=W4·(R+d / 2) / (Rd / 2)Formula 8 Assuming the second target wheel is the inner wheel and the fourth target wheel is the outer wheel, the wheel speed W2 of the second target wheel can be estimated using the following formula 9: W2=W4·(Rd / 2) / (R+d / 2)Formula 9 Where W4 is the wheel speed of the fourth target wheel whose wheel speed is known, and d represents the wheelbase, i.e., the distance between the left and right wheels on the same axle. R+d / 2 can be approximated as the turning radius of the outer wheel, and Rd / 2 can be approximated as the turning radius of the inner wheel.

[0084] The derivation principle of Formulas 8 and 9 is consistent with the front axle speed estimation process, that is, assuming that the wheels on both sides of the same axle rotate around the same steering center, the ratio of their wheel speeds is equal to the ratio of their respective turning radii.

[0085] S24: When the driving state is straight-line driving, determine that the wheel speed of the fourth target wheel is the same as the wheel speed of the second target wheel.

[0086] When the driving state is straight, since the theoretical rotational speeds of the left and right wheels are equal, the wheel speed of the fourth target wheel can be directly assigned to the wheel speed of the second target wheel.

[0087] S25: Estimate the rear axle speed based on the wheel speeds of the second and fourth target wheels.

[0088] Specifically, the average of the wheel speeds of the second and fourth target wheels can be used as the estimated rear axle speed.

[0089] In this embodiment, a feasible method for estimating the front and rear axle speeds is proposed when the transfer case output shaft speed signal is unavailable. By utilizing the wheel speed sensor signal on one side and combining it with the vehicle's driving state and basic geometric parameters, the overall axle speed, i.e., the front axle speed / rear axle speed, can be reliably estimated even when the transfer case output shaft speed signal and the wheel speed signal on the same side of the axle are both unavailable.

[0090] In some embodiments, when the number of the first target wheels is 2 or the number of the second target wheels is 2, if a mode switching request to enter 4H mode is received, a first prompt message is output, which is used to prompt the driver to prohibit switching to 4H mode.

[0091] Understandably, when the number of the first target wheels (wheels on the front axle with unavailable wheel speed signals) reaches two, it means that all wheel speed signals on that front axle are unavailable, making it impossible to estimate the front axle speed using a single valid wheel speed signal. Similarly, when the number of the second target wheels (wheels on the rear axle with unavailable wheel speed signals) reaches two, it means that all wheel speed signals on that rear axle are unavailable, making it impossible to estimate the rear axle speed using a single valid wheel speed signal. Without knowing the front or rear axle speeds, the speed difference between the front and rear axles cannot be accurately determined. In this situation, to avoid the drawback of accidentally entering 4H mode due to a failure to detect the speed difference in time, if a mode switching request to enter 4H mode is received, a first prompt message is output to remind the driver not to switch to 4H mode.

[0092] In this embodiment, when the wheel speed signals on both sides are unavailable, a preset protection strategy is executed. That is, if a mode switching request to enter 4H mode is received, a first prompt message is output to remind the driver not to enter 4H mode. This effectively prevents the drawback of accidentally entering 4H mode due to the failure to detect the large speed difference in time when the wheel speed signals on both sides are unavailable.

[0093] In some embodiments, determining whether a vehicle is in an abnormal wheel speed condition based on the speed difference includes: determining that the vehicle is in an abnormal wheel speed condition when the absolute value of the speed difference is greater than a preset speed difference threshold for a duration exceeding a first preset duration; and determining that the vehicle is not in an abnormal wheel speed condition when the absolute value of the speed difference is greater than the preset speed difference threshold for a duration not exceeding the first preset duration, or when the absolute value of the wheel speed difference is less than or equal to the preset speed difference threshold.

[0094] The preset speed difference threshold can be pre-calibrated to define the normal fluctuation boundary of the speed difference between the main drive shaft and the auxiliary drive shaft, and is used to measure whether the speed difference between the main drive shaft and the auxiliary drive shaft is within the allowable normal fluctuation range. The preset speed difference threshold is pre-calibrated based on a large amount of experimental data and statistical analysis, and represents the maximum random speed difference between the main drive shaft and the auxiliary drive shaft that may occur due to minor sensor errors and micro-inconsistencies in road surface conditions, under driving conditions with consistent tire condition and good road surface. For example, this preset speed threshold can be calibrated as 'a' rpm, which is converted from 2 ± 0.5 km / h, and the value of 'a' is related to the rolling radius of the wheel and the speed ratio.

[0095] If the calculated |Vd| is greater than the preset speed threshold, it indicates that the speed difference between the main drive shaft and the auxiliary drive shaft exceeds the allowable normal fluctuation range. To avoid inaccurate identification due to instantaneous fluctuations, a first preset duration is set. This first preset duration is used to confirm the persistence of the abnormal state and can be pre-calibrated to a relatively short duration, such as approximately 3 minutes. Only when the state where |Vd| is greater than the preset speed threshold continues for more than the first preset duration is the vehicle determined to have entered an abnormal wheel speed condition. This ensures that what is identified is a stable and continuous abnormal signal, rather than an instantaneous disturbance, thus improving the accuracy of identifying abnormal wheel speed conditions.

[0096] If the duration of |Vd| being greater than the preset speed threshold does not exceed the first preset duration, it indicates that the abnormal signal is transient. That is, the duration of the state where |Vd| is greater than the preset speed difference threshold is short and has not yet reached the judgment criteria for abnormal wheel speed conditions. In other words, although the instantaneous speed difference exceeds the standard, it has not formed a continuous trend. Therefore, it is first determined that there is no abnormal wheel speed condition, thus avoiding excessive intervention.

[0097] When |Vd| is less than or equal to the preset speed difference threshold, it means that the speed difference between the main drive shaft and the auxiliary drive shaft has not exceeded the allowable normal fluctuation range. It can be directly determined that the current wheel speed is not in an abnormal working condition, that is, the current wheel speed is in a normal working condition.

[0098] In this embodiment, when the current vehicle speed is low, a dual judgment mechanism combining a preset speed difference threshold and a first preset duration is introduced. The preset speed difference threshold defines an abnormal speed difference, which helps to filter out a large number of normal, minor fluctuations. The first preset duration confirms the persistence of the anomaly from a time perspective, effectively filtering out various instantaneous and occasional interference signals. The two work together to identify persistent inter-axle speed differences that exceed the normal allowable range, improving the accuracy and reliability of identifying abnormal wheel speed conditions. This ensures that subsequent decisions to intervene in the 4H mode switching are both timely and accurate, minimizing the impact of misjudgments on the driver's operation under normal conditions.

[0099] Implementation Method 2: When the current vehicle speed is greater than the preset vehicle speed threshold, determine the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the wheel speed of each wheel, and determine whether the vehicle is in an abnormal wheel speed condition based on the degree of slippage.

[0100] When the current vehicle speed exceeds the preset speed threshold, it indicates that the current speed is high. At higher speeds, the vehicle's driving state is more stable, but the baseline value of the speed difference increases. In this case, using the degree of slip, i.e., the ratio of the inter-axle speed difference to the speed of the main drive shaft, as the basis for judgment is more scientific.

[0101] Understandably, at higher vehicle speeds, the speed difference Vd increases with speed. Using a fixed speed difference threshold might be too sensitive at high speeds, misinterpreting normal driving fluctuations as abnormal wheel speed conditions. However, the slip degree Vs, being a dimensionless relative value, better reflects the essential physical differences in tires. Therefore, at higher vehicle speeds, using slip degree as the criterion for judging abnormal wheel speed conditions can improve the accuracy of identifying such conditions.

[0102] In some embodiments, determining the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the wheel speed of each wheel includes: determining the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the speed difference between the auxiliary drive shaft and the main drive shaft and the shaft speed of the main drive shaft.

[0103] For example, the degree of slippage can be the ratio between the speed difference between the auxiliary drive shaft and the main drive shaft and the shaft speed of the main drive shaft.

[0104] like Figure 1 As shown, assuming the main drive shaft is the rear axle and the auxiliary drive shaft is the front axle, then the first and second wheels are the left front wheel 101 and right front wheel 102, respectively, and the third and fourth wheels are the left rear wheel 103 and right rear wheel 104, respectively. The degree of slippage of the front axle relative to the rear axle is denoted as Vs. Combining the calculation formula for the speed difference Vd mentioned above, Vs can be calculated using the following formula 10: Vs=Vd / Vr=(Vr-Vf) / Vr Formula 10 In some embodiments, determining whether a vehicle is in an abnormal wheel speed condition based on the degree of slip includes: determining that the vehicle is in an abnormal wheel speed condition when the absolute value of the slip degree is greater than a preset slip degree threshold for a duration exceeding a second preset duration; and determining that the vehicle is not in an abnormal wheel speed condition when the absolute value of the slip degree is greater than the preset slip degree threshold for a duration not exceeding the second preset duration, or when the absolute value of the slip degree is less than or equal to the preset slip degree threshold.

[0105] The preset slip threshold is a dimensionless percentage value designed to define the normal boundary of slippage between the auxiliary drive shaft and the main drive shaft. The preset slip threshold can be pre-calibrated based on factors such as normal tire wear error, sensor system error, and reasonable dynamic fluctuations during high-speed driving. For example, the preset slip threshold can be calibrated to approximately 0.033.

[0106] If the calculated |Vs| is greater than the preset slip threshold, it indicates that |Vs| exceeds the allowable normal fluctuation range, meaning that the speed difference between axles cannot be explained by normal random factors, and an abnormal wheel speed condition is likely to have occurred. To avoid inaccurate identification due to instantaneous fluctuations, a second preset duration is set. This second preset duration is used to confirm the persistence of the abnormal state and can be pre-calibrated to a relatively short duration, such as around 3 minutes. Only when the state where |Vs| is greater than the preset slip threshold continues for more than the second preset duration is the vehicle determined to have entered an abnormal wheel speed condition. This ensures that what is identified is a stable and continuous abnormal signal, rather than an instantaneous disturbance, thus improving the accuracy of identifying abnormal wheel speed conditions.

[0107] If the duration of |Vs| being greater than the preset slip threshold does not exceed the second preset duration, it indicates that the abnormal signal is transient. That is, the duration of the state where |Vs| is greater than the preset slip threshold is short and has not yet reached the judgment criteria for abnormal wheel speed conditions. In other words, although the instantaneous slip degree exceeds the standard, it has not formed a continuous trend. Therefore, it is first determined that there is no abnormal wheel speed condition, thus avoiding excessive intervention.

[0108] When |Vs| is less than or equal to the preset slip threshold, it means that the speed difference between the main drive shaft and the auxiliary drive shaft has not exceeded the allowable normal fluctuation range. It can be directly determined that the current wheel speed is not in an abnormal working condition, that is, the current wheel speed is in a normal working condition.

[0109] In this embodiment, when the current vehicle speed is high, a dual judgment mechanism combining a preset slip degree threshold and a second preset duration is introduced. The preset slip degree threshold defines the abnormal slip degree, which helps to filter out a large number of normal slips. The second preset duration confirms the persistence of the anomaly from a time dimension, effectively filtering out various instantaneous and occasional interference signals. The two work together to identify persistent inter-axle relative slip that exceeds the normal allowable range, improving the accuracy and reliability of identifying abnormal wheel speed conditions. This ensures that subsequent decisions to intervene in the 4H mode switching are both timely and accurate, minimizing the impact of misjudgments on the driver's operation under normal conditions.

[0110] To further facilitate understanding of the wheel speed abnormality identification method provided in this application embodiment, the following explanation is based on Table 1. In Table 1, the preset vehicle speed threshold is 30 km / h, the preset speed difference threshold is 1 km / h, the preset slip degree threshold is 0.033, and the first and second preset durations are both 3 minutes. However, in specific implementations, the values ​​of the above-mentioned thresholds are not limited to the examples in Table 1. For ease of explanation, the unit of |Vd| in Table 1 is km / h converted from rpm; therefore, the preset speed difference threshold is also based on km / h.

[0111] Table 1

[0112] As can be seen from Table 1 above, the following situations exist for judging abnormal wheel speed conditions: When 0 < VehSpd ≤ 30, if |Vd| exceeds 1 km / h and the duration t exceeds 3 min, it is determined to be an abnormal wheel speed condition; if |Vd| exceeds 1 km / h but the duration t is less than or equal to 3 min, it is determined to be a normal wheel speed condition; if |Vd| is less than or equal to 1 km / h, it is determined to be a normal wheel speed condition.

[0113] When VehSpd > 30, if |Vs| exceeds 0.033 and the duration t exceeds 3 minutes, it is determined to be an abnormal wheel speed condition; if |Vs| exceeds 0.033 but the duration t is less than or equal to 3 minutes, it is determined to be a normal wheel speed condition; if |Vs| is less than or equal to 0.033, it is determined to be a normal wheel speed condition.

[0114] It should be noted that the judgments mentioned in Table 1 are independent; if the conditions are not met, the duration t needs to be reset. For example, if the duration of 0 < VehSpd ≤ 30 and |Vd| > 1 exceeds 3 minutes, it is judged as an abnormal wheel speed condition. If the vehicle accelerates to VehSpd > 30, |Vs| and vehicle speed need to be judged again to re-determine whether the current condition is an abnormal wheel speed condition, thus restarting the accumulation of duration. As another example, if the duration of 0 < VehSpd ≤ 30 and |Vd| > 1 exceeds 3 minutes, it is judged as an abnormal wheel speed condition. If |Vd| changes to |Vd| < 1, then the current condition needs to be re-determined, thus restarting the accumulation of duration.

[0115] In this embodiment, different judgment methods for abnormal wheel speed conditions are set based on different vehicle speed ranges. Combining the sensitivity advantage of inter-axle speed difference at low speeds with the stability and adaptability advantage of relative slip at high speeds, it ensures high reliability and accuracy in monitoring abnormal wheel speed conditions across the entire speed range from extremely low to maximum speed. This refined judgment across different speed segments allows for more accurate identification of abnormal wheel speed conditions, enabling intervention in 4H mode only when necessary. This ensures safety while maximizing the driver's operational freedom under normal conditions.

[0116] In some embodiments, to ensure the safety and reliability of wheel speed abnormality judgment and subsequent mode switching control, the wheel speed abnormality judgment process will not be performed if any of the following abnormal states are detected: related system failure, or unknown current vehicle drive mode. Related system failure refers to a subsystem directly related to four-wheel drive control and wheel speed monitoring (such as the four-wheel drive control unit itself, wheel speed sensor circuit, and related CAN communication network) reporting a clear fault code. At this time, the system's hardware or software environment is in an unhealthy state and does not have the conditions to perform reliable logical judgments. Unknown current vehicle drive mode means that it is impossible to clearly determine whether the transfer case is currently in 2H, 4H, or 4L mode. This may be due to a mode position sensor failure, a previous mode switch not being completed successfully, etc. A clear current mode is the basis for assessing whether to switch to 4H; if the mode is unknown, the mode switching logic cannot operate safely.

[0117] In this embodiment, when the state is abnormal, the abnormal wheel speed condition is not determined. This avoids executing logic that may lead to misjudgment when the state itself is abnormal or the data is unreliable. For example, it may prevent the failure to detect real risks and allow dangerous switching, or the failure to detect normal state and make unnecessary interventions, which may affect driving.

[0118] In step 203: When the vehicle is in an abnormal wheel speed condition, if the controller receives a mode switching request to enter 4H mode, switching to 4H mode is prohibited. This mode switching request refers to an electronic command signal generated by the driver operating the in-vehicle four-wheel drive mode selection switch, intending to change the transfer case from its current mode to 4H mode. This signal is sent to the controller (such as the transfer case controller or the vehicle controller). This mode switching request can be a mode switching request from 2H mode to 4H mode, or it can be a mode switching request from AWD mode to 4H mode; however, this embodiment does not specifically limit which mode to switch to 4H mode from.

[0119] Because the vehicle is currently in an abnormal wheel speed condition, even if the controller receives a mode switching request to enter 4H mode, it will not control the vehicle to enter 4H mode, but will instead prohibit the vehicle from entering 4H mode.

[0120] In some embodiments, if a mode switching request to enter 4H mode is received, then switching to 4H mode is prohibited, including: if a mode switching request to enter 4H mode is received, then the current mode switching state is set from an active state to an inactive state to prohibit switching to 4H mode.

[0121] Specifically, the controller can maintain a flag indicating the mode switching status, which represents whether a mode switching operation from the driver is currently permitted. When the mode switching status is valid, it means that mode switching can proceed normally, and the controller will respond to and execute the driver's mode switching request. When the mode switching status is invalid, it means that an abnormal wheel speed condition has been detected, and the controller will ignore the driver's mode switching request.

[0122] For example, the controller can continuously monitor the driver's mode switching requests. When it receives a mode switching request to enter 4H mode, it does not execute it immediately. Instead, it first calls the aforementioned wheel speed abnormality judgment logic to query the current vehicle condition. If the vehicle is in a wheel speed abnormality condition, the controller immediately sets the internal mode switching state from an active state to an inactive state. Since the mode switching state is now inactive, the controller determines that mode switching is not allowed and therefore does not send drive commands to the transfer case actuator. The driver's mode switching request is safely intercepted at the software level. When it is detected that the vehicle has moved out of the wheel speed abnormality condition and is in a normal wheel speed condition, the mode switching state is reset to an active state, thereby restoring the driver's normal control over mode switching.

[0123] In some embodiments, if a mode switching request to enter 4H mode is received when the vehicle is in the abnormal wheel speed condition, the method further includes: outputting a prompt message to inform the driver of the reason why entering 4H mode is prohibited.

[0124] For example, the controller can send specific prompts to the instrument panel or infotainment system via the CAN bus, such as displaying prompt text (e.g., abnormal tire speed, unable to complete mode switching), thereby informing the driver why the mode switching request was not responded to, ensuring that the driver clearly understands why the operation is restricted, and improving the transparency of human-machine interaction and driving experience.

[0125] Considering that even after the initial prompt message is output, there may still be situations where the driver forces operation or the vehicle mistakenly switches to 4H mode due to judgment delay, this application also proposes a tiered processing strategy for erroneous switching to 4H mode. This strategy aims to safely and effectively guide or forcibly exit the inappropriate 4H mode to protect the transmission system and ensure driving safety.

[0126] In some embodiments, the above method further includes the following steps S31 to S35: S31: Determine whether the vehicle meets the preset conditions for incorrectly switching to 4H mode.

[0127] Incorrectly entering 4H mode refers to entering 4H mode when it should not have been entered. This preset condition can include the following conditions 1 and 2: Condition 1: The vehicle is on a paved road.

[0128] Condition 2: The wheel speed difference rate exhibits an abnormal abrupt change before and after the vehicle enters 4H mode. Specifically, before entering 4H mode, the calculated wheel speed difference rate is greater than or equal to a first preset difference rate threshold; however, after entering 4H mode, this wheel speed difference rate rapidly decreases to below the first preset difference rate threshold. The reason for this abnormal abrupt change is that when a large wheel speed difference rate occurs on a well-adhesive paved road surface, forcibly entering 4H mode causes the mechanical locking mechanism in the transfer case to forcibly couple the front and rear axles to eliminate the speed difference, resulting in a reduction or disappearance of the wheel speed difference rate between the front and rear axles. This is achieved by forcing the front and rear axle speeds to synchronize through the internal constraint force of the transmission system, which may lead to tire slippage, parasitic power circulation in the drive chain, and a sharp increase in the temperature of components such as the transfer case and the final drive. In other words, ideally, if there is a speed difference between the front and rear axles before switching to 4H mode, but this speed difference disappears after entering 4H mode, then Condition 2 is satisfied.

[0129] If conditions 1 and 2 above are met, it is determined that the vehicle may have mistakenly switched to 4H mode and is in an unsafe operating state.

[0130] S32: If the preset conditions are met, output the second prompt message, which is used to prompt the driver to exit 4H mode.

[0131] Specifically, if the aforementioned preset conditions are met, it is determined that the vehicle is currently incorrectly in 4H mode and should exit this mode. At this point, a first-level intervention is initiated, and a second prompt message is output via the instrument panel or central control screen. This second prompt message clearly informs the driver that the current operating conditions are not suitable for using 4H mode and suggests that they manually exit. If the driver responds to the second prompt message and triggers a mode switching request to exit 4H mode, the second prompt message disappears, and the processing ends.

[0132] S33: If a mode switching request to exit 4H mode is received and no successful exit of 4H mode is detected within the third preset time period, the transfer case motor is controlled to trigger alternating positive and negative pulses with the maximum allowable operating current in order to attempt to exit 4H mode.

[0133] If a mode switching request to exit 4H mode is received, but the 4H mode has not been successfully exited within the third preset time period (e.g., 2 seconds), a secondary intervention is initiated. This involves controlling the transfer case motor to generate n (e.g., 3) alternating forward and reverse pulse currents at the maximum permissible operating current. This operation aims to apply a short, strong reciprocating impact torque to any potentially jammed mechanical locking fork or engagement sleeve. Through the alternating forward and reverse pulses, it attempts to overcome static friction or mechanical interference, providing an opportunity to exit 4H mode.

[0134] S34: If the number of times the forward and reverse alternating pulses are triggered with the maximum allowable operating current reaches a preset threshold, and the 4H mode is still not successfully exited, then braking control is applied to the reference wheel to attempt to exit the 4H mode. The reference wheel is the wheel with the lowest wheel speed among all the wheels of the vehicle.

[0135] If the 4H mode is not successfully exited after the preset threshold number of alternating forward and reverse pulses triggered with the maximum permissible operating current is reached, a level three intervention is initiated, namely, coordinated control through the braking system. The wheel with the lowest real-time wheel speed among the vehicle's four wheels is identified and designated as the reference wheel.

[0136] The braking system applies a preset braking force to the reference wheel, which is typically small. Simultaneously, the transfer case motor attempts to exit 4H mode again. Understandably, in 4H mode, the front and rear axles are rigidly locked, and the entire drivetrain experiences significant internal stress due to the speed difference between the front and rear axles. Applying slight braking to the slowest wheel will further reduce its speed briefly. Due to the vehicle's overall inertia, the remaining wheels and connected transmission components tend to maintain their original speeds. This results in a temporary reduction in torque on the transmission system, effectively reducing the force on the clamping mechanical locking sleeve. In this situation, combined with the transfer case motor, the probability of exiting 4H mode is increased.

[0137] S35: If the 4H mode is not successfully exited after braking control of the reference wheel, a third prompt message is output. The third prompt message is used to inform the driver that the 4H mode cannot be exited and the vehicle needs to be stopped.

[0138] If the 4H mode fails to exit successfully even after braking the reference wheel, it is determined to be a severe mechanical jam. In this case, a level four intervention is initiated, outputting a third prompt message that explicitly instructs the driver to perform a specific operation, such as displaying on the instrument panel, "4H mode cannot be exited. Please stop safely and shift into neutral." This third prompt message aims to guide the driver to stop, shift into neutral to unload the transmission system, and try switching modes again, or contact maintenance service. This avoids potential component damage caused by forcibly operating the system under continuous driving stress.

[0139] In this embodiment, in the case of mistakenly entering 4H mode, a multi-level intervention strategy is adopted, including outputting a second prompt message, controlling the transfer case motor to trigger alternating positive and negative pulses with the maximum allowable operating current, braking control of the reference wheel, and outputting a third prompt message. Under the premise of ensuring safety, this maximizes the probability of the vehicle returning to the normal driving mode in the case of mistaken entry and ultimately provides clear safety operation guidance to ensure the safety of the vehicle and the driver.

[0140] Figure 3 This is a schematic diagram of the structure of a vehicle control device provided in an embodiment of this application.

[0141] For example, such as Figure 3 As shown, the vehicle control device 300 includes: an acquisition module 301, used to acquire the wheel speed of each wheel of the vehicle and the current vehicle speed during vehicle operation; a judgment module 302, used to determine whether the vehicle is in an abnormal wheel speed condition based on the wheel speed of each wheel and the current vehicle speed; and a prohibition module 303, used to prohibit switching to the 4H mode if a mode switching request to enter the 4H mode is received when the vehicle is in the abnormal wheel speed condition.

[0142] It is not difficult to see that the embodiments of this application are device embodiments corresponding to the method embodiments described above, and the embodiments of this application can be implemented in conjunction with the method embodiments described above. The relevant technical details and technical effects mentioned in the method embodiments described above are still effective in the embodiments of this application, and will not be repeated here to reduce repetition.

[0143] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0144] For example, such as Figure 4 As shown, the electronic device 400 includes a memory 401 and a processor 402, wherein the memory 401 stores executable program code 4011, and the processor 402 is used to call and execute the executable program code 4011 to perform a vehicle control method.

[0145] Furthermore, embodiments of this application also protect an apparatus that may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a vehicle control method provided in embodiments of this application.

[0146] This embodiment can divide the device into functional modules based on the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0147] When each functional module is divided according to its corresponding function, the device may also include an acquisition module, a judgment module, and a prohibition module. It should be noted that all relevant content regarding the steps involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0148] It should be understood that the device provided in this embodiment is used to execute the above-described vehicle control method, and therefore can achieve the same effect as the above-described implementation method.

[0149] When using an integrated unit, the device may include a processing module and a storage module. When the device is applied to a vehicle, the processing module can be used to control and manage the vehicle's movements. The storage module can be used to support the vehicle in executing relevant program code.

[0150] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits shown in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0151] In addition, the device provided in the embodiments of this application may specifically be a chip, component or module. The chip may include a connected processor and a memory. The memory is used to store instructions. When the processor calls and executes the instructions, the chip can execute a vehicle control method provided in the above embodiments.

[0152] This application also provides a vehicle that includes the electronic devices described in the above embodiments.

[0153] This embodiment also provides a non-volatile storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement a vehicle control method provided in the above embodiment.

[0154] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned related steps to implement a vehicle control method provided in the above embodiment.

[0155] In this embodiment, the device, non-volatile storage medium, computer program product or chip are all used to execute the corresponding method provided above. Therefore, the beneficial effects that can be achieved can be referred to the beneficial effects of the corresponding method provided above, and will not be repeated here.

[0156] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0157] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0158] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for controlling a vehicle, characterized in that, The method includes: During vehicle operation, the wheel speed of each wheel of the vehicle and the current vehicle speed are obtained. Based on the wheel speed of each wheel and the current vehicle speed, determine whether the vehicle is in an abnormal wheel speed condition; If the vehicle is in the abnormal wheel speed condition and receives a mode switching request to enter 4H mode, then switching to 4H mode is prohibited.

2. The method according to claim 1, characterized in that, The step of determining whether the vehicle is in an abnormal wheel speed condition based on the wheel speed of each wheel and the current vehicle speed includes: When the current vehicle speed is less than or equal to a preset vehicle speed threshold, the speed difference between the auxiliary drive shaft and the main drive shaft is determined based on the wheel speed of each wheel, and the vehicle is judged to be in an abnormal wheel speed condition based on the speed difference. When the current vehicle speed is greater than the preset vehicle speed threshold, the degree of slippage of the auxiliary drive shaft relative to the main drive shaft is determined according to the wheel speed of each wheel, and the degree of slippage is used to determine whether the vehicle is in an abnormal wheel speed condition. In this configuration, one of the auxiliary drive shaft and the main drive shaft is the front axle, and the other is the rear axle.

3. The method according to claim 2, characterized in that, Each wheel includes: a first wheel and a second wheel at both ends of the auxiliary drive shaft, and a third wheel and a fourth wheel at both ends of the main drive shaft. Determining the speed difference between the auxiliary drive shaft and the main drive shaft based on the wheel speeds of each wheel includes: The axle speed of the auxiliary drive shaft is determined based on the wheel speed of the first wheel and the wheel speed of the second wheel. The shaft speed of the main drive shaft is determined based on the wheel speed of the third wheel and the wheel speed of the fourth wheel. The speed difference between the auxiliary drive shaft and the main drive shaft is determined based on the shaft speed of the auxiliary drive shaft and the shaft speed of the main drive shaft. or, Determining the degree of slippage of the auxiliary drive shaft relative to the main drive shaft based on the wheel speed of each wheel includes: The degree of slippage of the auxiliary drive shaft relative to the main drive shaft is determined based on the speed difference between the auxiliary drive shaft and the main drive shaft and the shaft speed of the main drive shaft.

4. The method according to claim 2, characterized in that, The step of determining whether the vehicle is in an abnormal wheel speed condition based on the speed difference includes: If the absolute value of the speed difference is greater than a preset speed difference threshold for a duration exceeding a first preset duration, the vehicle is determined to be in an abnormal wheel speed condition. If the duration for which the absolute value of the wheel speed difference is greater than the preset wheel speed difference threshold does not exceed the first preset duration, or if the absolute value of the wheel speed difference is less than or equal to the preset wheel speed difference threshold, it is determined that the vehicle is not in an abnormal wheel speed condition.

5. The method according to claim 2, characterized in that, The step of determining whether the vehicle is in an abnormal wheel speed condition based on the degree of slippage includes: If the absolute value of the slippage degree is greater than a preset slippage degree threshold for a duration exceeding a second preset duration, the vehicle is determined to be in an abnormal wheel speed condition. If the duration for which the absolute value of the slippage degree is greater than the preset slippage degree threshold does not exceed the second preset duration, or if the absolute value of the slippage degree is less than or equal to the preset slippage degree threshold, it is determined that the vehicle is not in an abnormal wheel speed condition.

6. The method according to any one of claims 1 to 5, characterized in that, If, when the vehicle is in the abnormal wheel speed condition, a mode switching request to enter 4H mode is received, the method further includes: Output a prompt message to inform the driver why entering the 4H mode is prohibited.

7. The method according to any one of claims 1 to 5, characterized in that, The provision that if a mode switching request to enter 4H mode is received, switching to 4H mode shall be prohibited includes: If a mode switching request to enter 4H mode is received, the current mode switching status is set from valid to invalid to prevent switching to 4H mode.

8. An electronic device, characterized in that, The electronic device includes: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 7.

9. A vehicle, characterized in that, The vehicle includes the electronic equipment as described in claim 8.

10. A non-volatile storage medium, characterized in that, The non-volatile storage medium stores a computer program that, when executed, implements the method as described in any one of claims 1 to 7.

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