Vehicle control method and vehicle

Abstract

This application discloses a vehicle control method and a vehicle, relating to the field of vehicle control technology. The vehicle includes a first power source and a second power source. The vehicle control method includes: determining the total required torque based on a torque request if a torque request exists, provided the vehicle meets preset shifting conditions; controlling the first power source to output torque based on a target pre-torque value, which is used to eliminate gear backlash in the first power source's transmission system; and controlling the first power source to respond to the torque request when its output torque reaches the target pre-torque value. The method of this application can effectively suppress vibration and noise during gear shifting, improving the smoothness and comfort of vehicle driving.

Description

Technical Field

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

[0002] Dynamic shift technology is widely used in the powertrain systems of electric and hybrid vehicles to improve shifting efficiency and driving smoothness. These systems typically include two drive units, one for the front axle and one for the rear axle, which need to coordinate torque output during shifts to adapt to changes in vehicle driving conditions.

[0003] In related technologies, dynamic shifting typically relies on the meshing and disengagement of gearbox gear pairs to complete gear changes. However, due to the inherent backlash between gears, when the torque direction changes from positive to negative, the gears undergo a process of engagement, disengagement, and re-engagement. If the rate of torque change during shifting is too rapid or the torque amplitude is too large, the impact and disengagement between gears will cause vibrations and abnormal noises in the transmission system, affecting driving comfort and system durability. Existing solutions mostly alleviate this problem by adjusting the shift timing or optimizing the gear profile design, but they still struggle to effectively suppress gear impact caused by torque polarity reversal.

[0004] Therefore, how to effectively suppress vibration and abnormal noise caused by gear backlash while ensuring timely response to vehicle torque requests has become an urgent technical problem to be solved in the field of electric vehicle power control. Summary of the Invention

[0005] This application aims to at least partially address one of the technical problems in the related art. To this end, the first objective of this application is to propose a vehicle control method that, during gear shifting, controls the first power source to output torque based on a target pre-torque value to eliminate gear backlash, and temporarily refrains from responding to external torque requests until its output torque reaches the target pre-torque value, while simultaneously transferring the total required torque to a second power source for response. In this way, the first power source focuses on completing its own reversal to eliminate gear impact during gear shifting, avoiding torque conflict and abnormal noise caused by responding to external torque requests, thereby effectively suppressing vibration and noise during gear shifting and improving driving smoothness and comfort.

[0006] The second objective of this application is to propose a vehicle.

[0007] To achieve the above objectives, a first aspect of this application provides a vehicle control method, the method comprising: determining a total required torque based on a torque request if a torque request exists, provided that the vehicle meets preset shifting conditions; controlling a first power source to output torque based on a target pre-torque value, the target pre-torque value being used to eliminate gear backlash in the transmission system of the first power source, wherein the first power source is controlled to respond to the torque request when the output torque of the first power source reaches the target pre-torque value; and controlling a second power source to output torque based on the total required torque.

[0008] According to the vehicle control method of this application embodiment, when it is determined that the vehicle meets the preset shifting conditions, if there is a torque request, the total required torque is determined based on the torque request, and the first power source is controlled to output torque based on a target pre-torque value. The target pre-torque value is used to eliminate gear backlash in the transmission system of the first power source. Specifically, when the output torque of the first power source reaches the target pre-torque value, the first power source is controlled to respond to the torque request, and the second power source is controlled to output torque based on the total required torque. Therefore, this method enables the first power source to output torque according to the target pre-torque value to eliminate gear backlash during gear shifting, and then respond to the torque request after the gear backlash elimination is completed. Simultaneously, the second power source undertakes the output of the total required torque, avoiding torque conflict caused by the first power source simultaneously handling backlash elimination and response torque. This effectively suppresses vibration and noise during gear shifting, improving the smoothness and comfort of vehicle driving.

[0009] According to one embodiment of this application, controlling the first power source to output torque based on a target pre-torque includes: controlling the output torque of the first power source to change to the target pre-torque value at a preset rate, wherein the preset rate is determined based on the rotational speed of the first power source, and the preset rate is negatively correlated with the rotational speed.

[0010] According to one embodiment of this application, the target pre-torque value is determined by: obtaining the current vehicle speed; determining the target pre-torque value based on the vehicle speed and a preset mapping relationship, wherein the preset mapping relationship is used to indicate the correspondence between the vehicle speed and the target pre-torque value.

[0011] According to one embodiment of this application, determining that the vehicle meets the preset shift conditions includes: acquiring the vehicle's gear change information, drive mode, and vehicle speed; when the vehicle speed is greater than a preset vehicle speed threshold, the current gear changes in reverse based on the gear change information, and the drive mode is a target drive mode, determining that the vehicle meets the preset shift conditions, wherein the reverse change indicates a shift from forward gear to reverse gear or vice versa, and the target drive mode is an electric four-wheel drive mode.

[0012] According to one embodiment of this application, the method further includes: controlling the first power source not to respond to the torque request during the process of the output torque of the first power source changing to the target pre-torque at the preset rate.

[0013] According to one embodiment of this application, the method further includes: before the output torque of the first power source changes at the preset rate, controlling the output torque of the first power source to a torque limit value, wherein the torque limit value is the minimum value between the absolute value of the requested torque of the first power source and the absolute value of the actual torque of the first power source.

[0014] According to one embodiment of this application, the method further includes: controlling the first power source to respond to the torque request when the output torque of the first power source reaches the target pre-torque value or the driving mode is not the target driving mode.

[0015] According to one embodiment of this application, the method further includes: determining that the output torque of the first power source has reached the target pre-torque value when the absolute value of the difference between the output torque and the target pre-torque value is less than a preset difference threshold.

[0016] According to one embodiment of this application, controlling the first power source to respond to the torque request includes: determining a first output torque of the first power source and a second output torque of the second power source based on the total required torque and a preset torque distribution relationship; controlling the first power source to output torque based on the first output torque, and controlling the second power source to output torque based on the second output torque, wherein the sum of the first output torque and the second output torque is the total required torque.

[0017] To achieve the above objectives, a vehicle is provided in the second aspect of this application, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described vehicle control method.

[0018] According to the embodiments of this application, by executing the above-described vehicle control method, the vehicle can effectively suppress vibration and noise during gear shifting, thereby improving the smoothness and comfort of driving the vehicle.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] Figure 1 This is a flowchart of a vehicle control method according to an embodiment of this application.

[0021] Figure 2 This is a flowchart illustrating a specific example of a vehicle control method according to this application.

[0022] Figure 3 This is a block diagram of a vehicle according to an embodiment of this application. Detailed Implementation

[0023] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0024] In the field of electric four-wheel drive vehicle control, to achieve dynamic switching between forward and reverse gears, the common approach is to directly adjust the direction of the output torque of the front axle motor, rapidly switching it from the torque direction corresponding to the current gear to the torque direction corresponding to the target gear. This approach is widely adopted primarily to achieve rapid response during gear shifting, meeting the expectations of drivers or autonomous driving systems for instantaneous changes in power.

[0025] However, this solution does not perform ideally when applied to scenarios requiring high smoothness and low noise and vibration. Specifically, its inherent rapid torque reversal design, aimed at optimizing shift response, inevitably compromises ride comfort and transmission system durability. For example, when the vehicle is traveling at low speeds, and the system detects the need to shift from drive (D) to reverse (R), this inherent contradiction causes noticeable vibrations and abnormal noises in the gear transmission system, manifesting as a jolt that is directly perceptible to the driver and passengers, and a mechanical impact sound from the gearbox.

[0026] In-depth analysis revealed that the root cause of the above problems lies in the fact that the gears in the transmission system are not in an ideal zero-backlash meshing state. There must be a physical clearance between the gears, which is allowed by design, namely tooth flank clearance. At the moment of torque switching, the tooth surfaces that were originally in contact with one side of the tooth profile will separate due to the reversal of the torque direction, cross the clearance, and collide with the tooth profile on the other side. This process of "contact-separation-re-contact" is accompanied by impact energy, which is particularly violent during rapid reversal, thus producing unacceptable vibration and abnormal noise.

[0027] To address the aforementioned issues, this invention proposes a vehicle control method that introduces a dedicated "pre-torque" phase. Before the first power source (front axle) formally responds to the load torque request, a target pre-torque value is actively output to compress and eliminate gear backlash in its transmission system. Simultaneously, the vehicle's immediate torque demand is transferred to the second power source (rear axle) for response. This solves the technical problems of gear impact and vibration noise caused by rapid torque reversal, achieving a significant improvement in shift smoothness while ensuring uninterrupted power delivery.

[0028] In one embodiment of this application, the vehicle may be a hybrid or pure electric vehicle, and its drive system includes at least two independent power sources: a first power source and a second power source. The first power source is mechanically coupled to the front axle of the vehicle to drive the front wheels; the second power source is mechanically coupled to the rear axle of the vehicle to drive the rear wheels. The first power source transmits power to the front axle via a first gearbox, which contains multiple gear pairs with inherent gear backlash. Similarly, the second power source transmits power to the rear axle via a second gearbox. The vehicle also includes a vehicle controller that communicates with electronic control units such as the first power source controller, the second power source controller, and the gearbox controller. The vehicle controller is responsible for acquiring signals from the vehicle's sensor network (including but not limited to vehicle speed sensors, gear position sensors, motor speed sensors, torque sensors, etc.), generating and sending control commands to each power source and the gearbox to execute a dynamic shifting process. Additionally, the vehicle includes a power battery for providing electrical energy to the first and second power sources.

[0029] The vehicle control method and vehicle proposed in this application are described below with reference to the accompanying drawings.

[0030] Figure 1 This is a flowchart of a vehicle control method according to an embodiment of this application.

[0031] like Figure 1 As shown, the vehicle control method of this application embodiment may include the following steps: S1, if the vehicle meets the preset shift conditions, and there is a torque request, then the total required torque is determined based on the torque request.

[0032] Specifically, the system determines whether the vehicle currently meets the preset shift conditions. If the vehicle meets the preset shift conditions, and there is a torque request, the total required torque is determined based on that request. In other words, the total required torque is only calculated if the vehicle meets the preset shift conditions and the driver or the vehicle itself has a clear torque requirement, thus ensuring that the torque control during the shift process meets the vehicle's actual operating needs.

[0033] In this application, preset shift conditions refer to the conditions that trigger a preset gear change. These conditions may include situations such as the vehicle's current speed falling within the preset speed range of the target gear, the driver triggering a shift command by operating the shift mechanism, or the vehicle automatically generating shift requirements based on driving conditions. Examples include, but are not limited to, speeds exceeding preset speed thresholds, gear reversals, and the drive mode being electric four-wheel drive. Reversal refers to the switching between forward and reverse gears. Torque request refers to an external or internal command generated by the vehicle controller or the driver's intent, requiring the power source to output a specified torque. Examples include, but are not limited to, parking torque requests from the vehicle controller, acceleration requests from the intelligent driving system, or target torque from pedal analysis. Total required torque refers to the total torque value that needs to be output by all power sources of the vehicle, calculated based on all torque requests. Examples include, but are not limited to, the total parking torque request issued and processed by the intelligent driving system in parking mode.

[0034] S2, control the first power source to output torque based on the target pre-torque value, the target pre-torque value is used to eliminate gear backlash in the transmission system of the first power source, wherein, when the output torque of the first power source reaches the target pre-torque value, control the first power source to respond to the torque request.

[0035] Specifically, when controlling the first power source, it can be controlled to output torque based on a target pre-torque value, which is used to eliminate gear backlash in the first power source's transmission system. When the output torque of the first power source reaches the target pre-torque value, it can be controlled to respond to the torque request. In other words, by outputting the target pre-torque value in advance to eliminate gear backlash in the first power source's transmission system, it is possible to avoid impact caused by gear backlash when the first power source outputs torque in response to a torque request, improving the smoothness of power output during gear shifts and enhancing the driving experience. Simultaneously, it allows the first power source to respond to the torque request only after preparation is complete, ensuring the timeliness and accuracy of torque output to meet power demands.

[0036] That is, before the output torque of the first power source reaches the target pre-torque value, it does not participate in responding to torque requests from the driver or system. Its primary task is to complete its own slow commutation, that is, to smoothly transition the torque to the pre-torque value. Only after the output torque of the first power source successfully reaches the target pre-torque value, indicating that gear backlash has been eliminated, does it release its power and begin to respond to torque requests.

[0037] The target pre-torque value refers to a torque reference value set for a specific purpose to eliminate or suppress gear backlash in the transmission system. Specifically, in one embodiment, the target pre-torque value is a target torque state that the first power source needs to achieve during the reversing process. The torque output in this state is sufficient to keep the tooth surfaces of the relevant gear pair in continuous contact, eliminating tooth backlash, and is typically less than the maximum torque required for normal vehicle driving or braking. For example, under static conditions with a vehicle speed of 0, the target pre-torque value can be a small positive torque, such as 2 Newton-meters; while during dynamic gear shifting at a certain vehicle speed, this value will increase accordingly based on the vehicle speed.

[0038] As a specific implementation method, the process of controlling the torque output of the first power source based on the target pre-torque value can be further refined. For example, it is necessary to first control the output torque of the first power source to decrease until its absolute value decreases to near zero, and then increase it in the opposite direction until the target pre-torque value is reached. This process can be a linear change. More generally, the method of controlling the output torque of the first power source can be implemented in various ways. For example, it can include, but is not limited to, using a fixed torque change slope, or using a torque change slope based on the real-time change of motor speed, or using a time-based curve function to control the torque to transition from the current value to the target pre-torque value. At the software or logic level, the vehicle controller can achieve precise torque control by executing a proportional-integral-derivative control algorithm or a model predictive control algorithm, taking the current actual torque value of the first power source, motor speed, target pre-torque value, etc., as inputs, and the torque command of the first power source as the output.

[0039] S3 controls the second power source to output torque based on the total required torque.

[0040] Specifically, when the vehicle meets the preset shifting conditions, the second power source (rear axle) can be controlled to output torque based on the total required torque determined in step S1. This means that throughout the entire vehicle shifting process, the rear axle independently or primarily assumes all responsibility for driving the vehicle, thereby ensuring the continuity of vehicle power and immediate response to external requests, without the driver perceiving a power interruption. Through this design, the front axle's shifting process becomes smooth and focuses on eliminating gear backlash, while the rear axle is responsible for bearing the power demand. Together, they resolve the contradiction between smooth shifting and continuous power.

[0041] For example, when a vehicle starts, it needs to perform a shifting operation from forward to reverse or vice versa. The rear axle outputs the corresponding torque based on the depth of the driver's accelerator pedal press to meet the driving power requirements. The front axle only needs to gradually complete the pre-torque operation to eliminate gear backlash. It does not need to simultaneously take into account power output and backlash elimination. Therefore, there will be no shifting shock due to sudden power changes, nor will there be any power interruption causing the vehicle to jerk.

[0042] Therefore, during gear shifting and reversing, the first power source specifically handles pre-torque to eliminate gaps, making the process smooth and controllable. It does not rapidly change the magnitude and direction of torque output in order to respond to torque demand, thus avoiding the impact and jerking caused by gear collisions. Meanwhile, the second power source continuously undertakes the output of the total required torque, ensuring that the vehicle's power is not interrupted and that the driver does not feel the jolt caused by a lack of power. It takes into account both the smoothness of gear shifting and the continuity of power, which not only improves the riding experience but also meets the vehicle's real-time power demand, solving the problem of impact, jerking, or power interruption that easily occurs during existing gear shifting processes.

[0043] According to one embodiment of this application, controlling a first power source to output torque based on a target pre-torque includes: controlling the output torque of the first power source to change to the target pre-torque value at a preset rate, wherein the preset rate is determined based on the rotational speed of the first power source, and the preset rate is negatively correlated with the rotational speed.

[0044] Specifically, to further optimize the smoothness of the pre-torque application process in the above embodiments and prevent sudden torque changes from causing new shocks to the transmission system, this application also provides the following preferred solution. In a preferred embodiment, the output torque of the first power source can be controlled to gradually change to the target pre-torque value at a preset rate. This preset rate is not a fixed constant, but is dynamically determined based on the current speed of the first power source, and the two are negatively correlated.

[0045] Specifically, the preset rate can be determined by the vehicle controller acquiring the current speed of the primary power source (such as a motor) in real time and then querying a two-dimensional mapping table pre-stored in the controller. This table defines the most suitable torque change rate (gradient) for different speed values. For example, when the motor speed is 0, the preset rate can be relatively large, reaching 5 Nm / s, so that the pre-torque can be established quickly; when the motor speed increases to 2000 rpm, the preset rate decreases to 1 Nm / s to ensure a smooth gear meshing process.

[0046] The mathematical relationship can be expressed as: Preset speed = f (motor speed), where f is a monotonically decreasing function. The technical principle behind this design is that when the motor rotates at high speed, its internal and transmission system inertia is large. If a pre-torque in the opposite direction is applied rapidly under these conditions, the inertial force and electromagnetic force superimposed can easily generate severe mechanical shock. Conversely, at low speeds, the system inertia is small, allowing for faster torque build-up to shorten the response time. This approach achieves a balance between smoothness and timeliness in the pre-torque application process, thus further suppressing vibration from the root of mechanical dynamics. This avoids the dilemma of excessively slow low-speed response or excessive high-speed shock that may occur when directly using a fixed gradient.

[0047] Those skilled in the art will understand that alternative structures achieving the same purpose include: the preset rate can be determined based on vehicle speed, the input shaft speed of the transmission, or the torque difference between the front and rear axles. For example, determining the preset rate based on vehicle speed, and using a lower gradient at higher vehicle speeds, can also achieve a similar smooth effect. Specifically, in real-world vehicle testing, a switching gradient of 3 to 5 Nm / s has a significant effect on solving the problem. This preset rate is preferably selected in the range of 0.5 to 10 Nm / s, or it can be indirectly defined using the equivalent torque change time (e.g., controlling the entire reversing process within 2 to 3 seconds). Furthermore, the preset rate is not limited to the above linear relationship; it can also be in the form of exponential decay or a piecewise function, as long as its overall trend is negatively correlated with the rotational speed.

[0048] Therefore, regardless of the specific function form used, the pre-torque build-up process can be flexibly adjusted according to the current operating state of the system. It can quickly complete the pre-torque loading when the inertia is small to meet the power response requirements, and slow down the torque change rhythm when the inertia is large to avoid the transmission system shock caused by sudden torque changes. This fundamentally optimizes the noise performance of the power switching process, improves the smoothness and ride comfort of the vehicle during driving, and also reduces the impact load on the transmission components, extending the service life of the components.

[0049] According to one embodiment of this application, the target pre-torque value is determined by: obtaining the current vehicle speed; and determining the target pre-torque value based on the vehicle speed and a preset mapping relationship, wherein the preset mapping relationship is used to indicate the correspondence between the vehicle speed and the target pre-torque value.

[0050] Specifically, to further optimize the method for determining the target pre-torque value in the above embodiments, enabling it to adapt to different driving conditions and avoid the incompatibility caused by a single fixed value, this application also provides the following preferred solution. When controlling the output target pre-torque value of the first power source, the magnitude of the target pre-torque value is a key parameter affecting the gear backlash elimination effect and overall smoothness. In a preferred embodiment, the current vehicle speed can be obtained, and then the target pre-torque value can be determined based on the vehicle speed and a preset mapping relationship. The preset mapping relationship is used to indicate the correspondence from vehicle speed to the target pre-torque value. For example, the mapping relationship can be a one-dimensional lookup table function.

[0051] In a specific example, when the vehicle is stationary (speed 0), the target pre-torque is set to a first preset value, such as 2 Nm. This relatively small pre-torque is sufficient to engage the gears in a static state, preparing for subsequent gear changes. When the vehicle enters a dynamic shifting process, such as when the speed reaches 1.5 to 2 km / h, the target pre-torque is increased to a second preset value, such as 4 to 5 Nm or higher. That is, in a dynamic state, the gears within the transmission have their own inertia and bear a certain load, requiring a larger pre-torque to reliably eliminate backlash and prevent the gears from disengaging again during gear changes.

[0052] The relationship between vehicle speed and pre-torque can be a positive linear correlation or a step function. That is, the higher the vehicle speed, the greater the rotational inertia and dynamic load within the transmission system. To overcome these additional dynamic effects, a larger pre-torque is needed to firmly engage the gear pairs. This approach ensures that the target pre-torque value always matches the vehicle's actual dynamic operating conditions. Using a smaller pre-torque value at low speeds avoids unnecessary torque fluctuations and energy consumption; using a larger pre-torque value at high speeds ensures reliable clearance elimination. Its advantage lies in avoiding the problems of insufficient pre-torque leading to incomplete clearance elimination (still risking abnormal noise) or excessive pre-torque causing additional load on the transmission or even generating new shocks.

[0053] Those skilled in the art will understand that, in addition to vehicle speed, other parameters such as motor temperature, transmission oil temperature, and battery charge can also be used as auxiliary inputs to determine the target pre-torque value. For example, in low-temperature environments, the pre-torque value can be appropriately increased to compensate for changes in lubricating oil damping. Furthermore, the preset mapping relationship is not limited to simple linear or stepwise mappings; it can also be a nonlinear mapping established through machine learning or neural network models, as long as its core logic is to input vehicle speed and output pre-torque value.

[0054] In other words, by establishing a preset mapping relationship between vehicle speed and pre-torque value, the pre-torque can be provided to match the vehicle at different driving speeds, thereby avoiding unnecessary additional resistance or impact on the transmission system caused by applying excessive pre-torque force at low speeds. Secondly, during dynamic gear shifting at higher speeds, the pre-torque value increases accordingly to overcome the separation tendency of the gear pair due to rotational inertia, ensuring that gear backlash is reliably eliminated, thereby effectively suppressing abnormal noise and vibration. Finally, this mapping relationship ensures that the pre-torque value is always adapted to the current dynamic conditions of the vehicle (such as vehicle speed), realizing adaptive adjustment of pre-torque output, and optimizing the smoothness, stability, and response efficiency of the transmission system as a whole.

[0055] Therefore, by adaptively adjusting the target pre-torque value based on vehicle speed, the gear backlash elimination effect and the smoothness of the transmission system can be balanced under different driving scenarios. This reduces the probability of gear impact noise during shifting and reversing, and also reduces unnecessary power loss and component load, effectively improving the reliability of the vehicle transmission system and driving comfort.

[0056] According to one embodiment of this application, determining that a vehicle meets preset shift conditions includes: acquiring vehicle gear change information, drive mode, and vehicle speed; when the vehicle speed is greater than a preset speed threshold, the current gear changes in reverse based on the gear change information, and the drive mode is the target drive mode, determining that the vehicle meets the preset shift conditions, wherein the reverse change indicates a shift from forward gear to reverse gear or vice versa, and the target drive mode is an electric four-wheel drive mode. The preset speed threshold can be determined according to actual conditions.

[0057] Specifically, in order to accurately identify the specific shifting scenarios requiring the aforementioned noise elimination control and avoid unnecessary pre-torque control and front axle response limitation, this application also provides the following preferred solution. As mentioned above, the method of this application begins with the general premise of "determining that the vehicle meets preset shifting conditions." In a preferred embodiment, this determination process can be implemented through a multi-condition logical AND decision.

[0058] First, the vehicle's gear shift information, drive mode, and speed are acquired. The vehicle is deemed to meet the preset shift conditions only if all three of the following conditions are met: Condition 1: The vehicle speed is greater than a preset speed threshold (e.g., the speed is greater than 0, indicating the vehicle is moving); Condition 2: Based on the gear shift information, it is determined that the current gear has undergone a reverse shift, specifically a shift from drive (D) to reverse (R), or vice versa; Condition 3: The current drive mode is the target drive mode, which is the electric four-wheel drive mode. These three conditions correspond to the dynamic, reversing, and four-wheel drive dimensions, accurately pinpointing the root cause of the vibration and abnormal noise issues.

[0059] For example, when shifting gears at a static position (vehicle speed = 0), the kinetic energy of the gear impact is very small; when shifting gears in the same direction, the torque direction does not reverse; and in non-four-wheel drive mode, the front axle may not actively output torque. Therefore, by considering these three conditions, the control strategy can be effectively prevented from being mistakenly triggered in unnecessary scenarios, such as shifting from P to D when the vehicle is stationary, or shifting from N to D in two-wheel drive mode. Its advantage lies in saving system computing resources and avoiding unnecessary torque intervention, thereby improving the intelligence and efficiency of the entire control system.

[0060] Those skilled in the art will understand that the preset vehicle speed threshold is not limited to 0, but can also be a positive value greater than 0, such as 3 kilometers per hour, to prevent false triggering during extremely low-speed crawling; or, a vehicle speed limit can be added, such as 50 kilometers per hour, because the risk and probability of high-speed shifting are different. The three sensor signals can be checked simultaneously within a single control cycle, and a logical truth value of "condition met" is output only when all three inputs are true. Furthermore, the preset shifting conditions are not limited to the above three, and can also include other auxiliary conditions, such as "brake pedal is depressed" or "shifting request remains valid for a certain period of time," to further filter out momentarily falsely triggered shifting signals.

[0061] Therefore, by judging the above conditions, the target shifting scenarios that are prone to front axle vibration and abnormal noise can be accurately identified. It will not miss the working conditions that need to eliminate abnormal noise control, nor will it mistakenly activate the control strategy in irrelevant scenarios. While effectively solving the problem of vibration and abnormal noise during reverse shifting in electric four-wheel drive vehicles, it minimizes the interference of torque control on the normal driving logic of the vehicle, reduces unnecessary computing power occupation of the control system, improves the accuracy and reliability of vehicle shifting control, and improves the user's driving experience.

[0062] According to one embodiment of this application, the vehicle control method further includes: controlling the first power source not to respond to torque requests during the process of the output torque of the first power source changing to the target pre-torque at a preset rate.

[0063] Specifically, to ensure the purity of the pre-torque build-up process and prevent external sudden torque requests from interfering with its execution, this application also provides the following preferred solution. As mentioned above, during the process of controlling the output target pre-torque value of the first power source, especially during the critical stage where its torque changes from the current value to the target pre-torque value at a preset rate, any torque request from the driver or the system may cause interference. In a preferred embodiment, while the output torque of the first power source is changing towards the target pre-torque value at a preset rate, the first power source can be controlled not to respond to any external torque requests. This means that during this period, the first power source is systematically shielded from its normal torque response responsibilities, and its only task is to smoothly execute torque commutation according to a predetermined gradient until the target pre-torque value is reached. All external torque requests that should be borne by the first power source will be fully borne by the second power source (rear axle).

[0064] For example, when a driver is parking and the vehicle is transitioning from forward to reverse, if the driver suddenly increases the accelerator pedal opening, the vehicle controller will recognize this increased torque request. However, it will not allocate this increase to the front axle; instead, it will send all commands to the rear axle. The torque command to the front axle will remain completely unaffected, continuing its pre-torque build-up process. The underlying principle is that by forcibly disconnecting the response link between the primary power source and the external torque request, the independence and integrity of the pre-torque application process are ensured. This avoids torque output jumps or interruptions caused by external interference, thereby guaranteeing the stable execution of the gear backlash elimination action.

[0065] Those skilled in the art will understand that the non-responsiveness to torque requests described herein does not mean a complete physical disconnection, but rather that at the software control level, the vehicle controller ignores torque request inputs from driving intentions or the ADAS system when calculating the torque command for the front axle. For example, when the commutation flag is active, the target front axle torque value is forced to equal the target pre-torque value or its intermediate transition value, and the driving intention torque request is bypassed or set to zero. Furthermore, the time period for non-responsiveness to torque requests is not limited to the torque change process, but can also extend to before and after the commutation process; for example, the restriction may begin a short period before the commutation is determined to have started.

[0066] Therefore, even if there are sudden changes in torque demand, the process of pre-torque buildup and eliminating gear backlash will not be interrupted. It will not cause shocks due to incomplete elimination of backlash before participating in torque output, nor will torque jumps disrupt the rhythm of pre-torque buildup. This ensures that the pre-torque control process remains smooth and stable, ultimately guaranteeing driving comfort during power switching, while reducing impact wear on the gear mechanism and extending the service life of the transmission system.

[0067] According to one embodiment of this application, the vehicle control method further includes: before the output torque of the first power source changes at a preset rate, controlling the output torque of the first power source to a torque limit value, wherein the torque limit value is the minimum value between the absolute value of the requested torque of the first power source and the absolute value of the actual torque of the first power source.

[0068] Specifically, to achieve a smooth, shock-free initial transition before the first power source enters the formal pre-torque application process, this application also provides the following preferred solution. As mentioned above, at the start of the commutation process, the first power source may be in a state of large torque output in either the forward or reverse direction. While a preset gradient could be used to achieve a direct decrease from this state, finer control can further reduce the initial impact. In a preferred embodiment, before the output torque of the first power source changes to the target pre-torque value at a preset rate, the output torque of the first power source is first limited to a torque limit. This torque limit (Reset value) is specifically defined as the smaller of the absolute value of the requested torque of the first power source and the absolute value of the actual torque of the first power source.

[0069] For example, assuming the filtered front motor wheel-end torque request is 50 Nm, while the actual front motor wheel-end torque is only 30 Nm, then 30 Nm is selected as the initial torque limit; conversely, if the request is 20 Nm and the actual torque is 40 Nm, then 20 Nm is selected. By instantaneously limiting the torque capability of the first power source to this small absolute value, the output torque is first pulled to a level closer to 0 Nm and more stable, and then, starting from this limit value, it transitions to the target pre-torque value at a preset rate. The technical principle is to use a low-pass or minimum value algorithm to filter out the difference between the requested torque and the actual torque, actively eliminating any possible errors or abrupt changes between them, thereby creating a smooth control starting point. This avoids the control overshoot or path dependence that might result from a linear decrease in torque from a high level, ensuring that the entire commutation process is in a controllable and smooth state from the very first step.

[0070] Those skilled in the art will understand that the torque limit can be calculated based on filtered values ​​for further smoothing. The torque limit is output via a minimum value selector after receiving the filtered absolute value of the requested torque at the front motor wheel end and the absolute value of the actual torque at the front motor wheel end. Furthermore, the determination of the smaller value is not limited to absolute value comparison; it can also directly compare signed numerical values ​​and take the one with the smaller absolute value.

[0071] Therefore, by using the above-mentioned torque limit initialization based on the minimum value of the requested and actual torque, a flexible and jitter-free starting point is provided for subsequent pre-torque application, thereby suppressing the impact of control from the source.

[0072] According to one embodiment of this application, the vehicle control method further includes: controlling the first power source to respond to a torque request when the output torque of the first power source reaches a target pre-torque value or the driving mode is not the target driving mode.

[0073] Specifically, to accurately determine when the pre-torque application is completed and accordingly safely and timely restore the torque response function of the first power source, this application also provides the following preferred solution. As mentioned above, the completion of pre-torque application is a prerequisite for releasing the front axle capacity and enabling it to participate in load response. In a preferred embodiment, the method further includes a step of exiting the judgment and restoring control: if the output torque of the first power source successfully reaches the target pre-torque value, or if the vehicle's current drive mode is no longer electric four-wheel drive mode, the restriction on the first power source is released, and its response torque request is restored.

[0074] Two exit conditions are set: successful achievement of the target and mode change. The first condition is normal exit, where the primary power source has smoothly completed the commutation, its output torque has stabilized near the target pre-torque value, gear backlash has been effectively eliminated, and its torque output capability can be safely restored. The second condition is abnormal exit or scenario change, such as when the driver manually deactivates four-wheel drive mode and switches to two-wheel drive mode during commutation. In this case, pre-torque control by the front axle is no longer necessary, and the front axle's capability should be immediately released to restore normal function, even if the pre-torque process is not yet complete. The technical principle is to provide a safety mechanism to ensure that the system will not lock the primary power source in a restricted state for an extended period under any circumstances. Normal exit ensures accurate function switching, while abnormal exit ensures system robustness and availability. This avoids power loss or response delays caused by control logic deadlock or misjudgment.

[0075] Those skilled in the art will understand that, in addition to the two conditions mentioned above, other conditions can be added, such as "commutation process timeout," as supplementary exit conditions. Specifically, it may include an OR gate, whose two inputs are respectively connected to a torque difference less than a threshold flag and a non-electric four-wheel drive mode flag. Furthermore, the recovery response is not limited to immediately restoring full capability; it can also be gradually restored according to a specific gradient, for example, releasing the front axle capability to a level matching the requested torque according to a gradient related to the motor speed.

[0076] Therefore, by adopting the aforementioned limiting features based on reaching the target pre-torque value or changing the mode as the exit condition, the timing of front axle torque recovery is ensured to be precise and safe, thereby guaranteeing the reliability and adaptability of the entire control method.

[0077] According to one embodiment of this application, the vehicle control method further includes: determining that the output torque of the first power source has reached the target pre-torque value when the absolute value of the difference between the output torque and the target pre-torque value is less than a preset difference threshold. The preset difference threshold can be determined according to actual conditions.

[0078] Specifically, to objectively and stably determine whether the output torque of the first power source has accurately reached the target pre-torque value and to avoid misjudgments caused by sensor noise or control errors, this application also provides the following preferred solution. As mentioned above, determining that the target pre-torque value has been reached is a key prerequisite for releasing the front axle's capability. In a preferred embodiment, this judgment process is not a simple numerical comparison, but rather based on a difference threshold. Specifically, the difference between the output torque of the first power source and the target pre-torque value can be calculated in real time. Only when the absolute value of this difference is less than a preset difference threshold is it determined that the output torque of the first power source has reached the target pre-torque value. For example, if the target pre-torque value is -5 Nm and the current actual output torque is measured to be -4.8 Nm, the difference is 0.2 Nm. If the preset difference threshold is set to 0.5 Nm, it is determined that the target has been reached.

[0079] In other words, the measurement and control of physical quantities will always involve a certain amount of noise and static error. Demanding exact equality (difference = 0) is unrealistic and will cause the control program to oscillate repeatedly around the target value or fail to converge. By using an externally calibrable threshold, a reasonable allowable range can be flexibly set based on the accuracy and vibration noise level of the control system. Its advantage lies in greatly improving the stability and robustness of the system in practical applications, avoiding frequent "reach-exit-rereach" cycles caused by small fluctuations in the control loop. Furthermore, the pre-torque values ​​for different gears require sign correction. For example, in D gear, the target pre-torque value is positive; in R gear, the pre-torque value obtained from the lookup table needs to be multiplied by -1 to obtain a negative target value before calculating the difference.

[0080] Those skilled in the art will understand that the preset difference threshold can be determined through actual vehicle calibration, for example, by adjusting based on feedback data from vibration sensors. Specifically, before calculating the difference, the pre-torque value is first corrected for sign based on the current gear, then the absolute value of the difference is calculated and compared with the preset difference threshold. By employing the aforementioned limiting feature based on the preset difference threshold to determine the achievement of the target value, the uncertainty caused by measurement and control errors is effectively eliminated, thereby making the decision on front axle capability recovery more stable and reliable. Furthermore, the calculation of the difference can directly compare the filtered requested torque with the corrected pre-torque value, making the judgment smoother.

[0081] Therefore, by using a preset difference threshold for judgment, it is possible to ensure both control precision and improved system stability. This provides a reliable basis for the smooth release of front axle power and the smooth switching between two-wheel drive and four-wheel drive modes, avoiding problems such as power connection jerking and mechanical shock caused by misjudgment, and optimizing the overall driving experience.

[0082] According to one embodiment of this application, controlling a first power source to respond to a torque request includes: determining a first output torque of the first power source and a second output torque of the second power source based on the total required torque and a preset torque distribution relationship; controlling the first power source to output torque based on the first output torque, and controlling the second power source to output torque based on the second output torque, wherein the sum of the first output torque and the second output torque is the total required torque.

[0083] Specifically, to achieve smooth and efficient torque coordination and distribution with the second power source after the first power source recovers its torque response, ensuring the continuity and consistency of vehicle power output, this application also provides the following preferred solution. As mentioned above, after the first power source completes pre-torque and recovers its response, it needs to jointly respond to the torque request with the second power source, which previously bore the entire load alone. In a preferred embodiment, this torque distribution process follows a preset rule. Specifically, when controlling the first power source to recover its torque response request, the vehicle controller first calculates the first output torque that the first power source should bear and the second output torque that the second power source should bear, based on the total required torque and the preset torque distribution relationship.

[0084] Then, simultaneously, the first power source outputs based on the first output torque, and the second power source outputs based on the second output torque, ensuring that the sum of the first and second output torques is strictly equal to the total required torque. This preset torque distribution relationship can be based on dynamic changes in vehicle status, such as vehicle speed, battery state of charge, or the vertical load distribution ratio between the front and rear axles. For example, in a parking scenario, after pre-torque is completed, the system can smoothly transition from a state where the rear axle bears 100% of the load to a distribution state where the front and rear axles each bear 50%. The technical principle is that by managing the torque output of the front and rear axles through a clear, preset mathematical relationship, torque jumps caused by sudden intervention of the front axle are avoided, thus ensuring a smooth and imperceptible vehicle power response. This not only ensures power continuity during steering but also ensures the continuity of torque distribution after steering, achieving a closed-loop seamless connection of the entire control process.

[0085] Those skilled in the art will understand that the preset torque distribution relationship can be a fixed coefficient or a function based on vehicle speed or pedal opening. Furthermore, the distribution relationship is not limited to a simple proportional distribution; it can also be a more complex distribution strategy based on optimization, such as minimum energy consumption distribution.

[0086] Therefore, by adopting the above-mentioned method of front and rear axle torque coordination based on preset allocation relationship, a smooth transition from commutation control to normal drive can be achieved, thereby making the entire control method of the present invention exhibit excellent stability and coordination from triggering to exiting.

[0087] In summary, as a specific example, a vehicle supporting electric four-wheel drive is performing an automatic parking operation. During the process of reversing into the parking space, due to the need to adjust the space in front, the automatic driving system triggers a dynamic switch from reverse gear (R gear) to drive gear (D gear), at which point the vehicle still has a speed of approximately 2 kilometers per hour.

[0088] At time T0, the vehicle controller detects that the above conditions meet the preset shift conditions and identifies a creeping torque request of -30Nm. The vehicle controller immediately determines the total required torque to be -30Nm. Subsequently, the vehicle controller initiates the commutation control strategy. It limits the maximum torque output capability of the front axle to the smaller of the absolute value of the filtered requested torque and the absolute value of the actual torque (for example, if the current actual torque is -20Nm and the request is -30Nm, then it is limited to 20Nm). Immediately afterwards, the vehicle controller instructs the front axle's torque target value to transition to the target pre-torque value (based on the current vehicle speed of 2kph, determined by a lookup table to be +5Nm) according to a gradient (e.g., 2Nm / s) based on the front motor speed. During this process, the vehicle controller completely shields the front axle from the response to external torque requests; the only task of the front axle is to perform this "slow commutation" from -20Nm to 0 and then to +5Nm.

[0089] Simultaneously, starting from time T0, the vehicle controller instructs the rear axle to output torque based on the total torque demand minus 30 Nm. The vehicle's power demand in reverse mode is entirely provided by the rear axle, ensuring uninterrupted power during reversing.

[0090] At time T0+1.5 seconds, the front axle torque successfully transitions to a pre-torque value of +5Nm. At this point, the vehicle controller detects that the absolute value of the difference between the actual output torque of the front axle and the target pre-torque value of +5Nm is less than 0.1Nm (less than a preset difference threshold), confirming that the pre-torque is complete. The vehicle controller immediately releases the restriction on the front axle and, based on a new preset distribution relationship (e.g., 50% for each axle at low speeds), instructs the front axle to output -15Nm and the rear axle to output -15Nm, with the sum remaining at -30Nm, achieving a coordinated response from both the front and rear axles.

[0091] Therefore, in this scenario, users can hardly feel the jolts caused by gear shifting or hear any mechanical noises from the transmission. The vehicle smoothly completes the speed and direction change from reversing to moving forward, improving the user experience and system reliability of the automatic parking system.

[0092] The following is combined Figure 2 The method described in this application is used to describe the method.

[0093] As a specific example, the vehicle control method of this application may include the following steps: S101 obtains information on vehicle gear changes, drive mode, and vehicle speed.

[0094] S102, determine whether the vehicle speed is greater than a preset vehicle speed threshold, determine whether the current gear has changed in the opposite direction based on the gear change information, and whether the drive mode is electric four-wheel drive mode. If yes, proceed to step S103; if no, proceed to step S101.

[0095] S103, if there is a torque request, the total required torque is determined based on the torque request, and the target pre-torque value is determined according to the vehicle speed and the preset mapping relationship.

[0096] S104 controls the output torque of the first power source to change to the target pre-torque value at a preset rate and controls the second power source to output torque based on the total required torque.

[0097] S105, determine whether the output torque of the first power source has reached the target pre-torque value or whether the drive mode is not the target drive mode. If yes, proceed to step S106; if no, proceed to step S104.

[0098] S106, based on the total required torque and the preset torque distribution relationship, determines the first output torque of the first power source and the second output torque of the second power source.

[0099] S107, control the first power source to output torque based on the first output torque, and control the second power source to output torque based on the second output torque, wherein the sum of the first output torque and the second output torque is the total required torque.

[0100] In summary, according to the vehicle control method of this application embodiment, when it is determined that the vehicle meets the preset shifting conditions, if a torque request exists, the total required torque is determined based on the torque request, and the first power source is controlled to output torque based on a target pre-torque value. The target pre-torque value is used to eliminate gear backlash in the transmission system of the first power source. When the output torque of the first power source reaches the target pre-torque value, the first power source is controlled to respond to the torque request, and the second power source is controlled to output torque based on the total required torque. Therefore, this method can effectively suppress vibration and noise during gear shifting, improving the smoothness and comfort of vehicle driving.

[0101] Corresponding to the above embodiments, this application also proposes a vehicle.

[0102] like Figure 3 As shown, the vehicle 200 in this embodiment may include: a memory 210, a processor 220, and a program stored in the memory 210 and executable on the processor 220. When the processor 220 executes the program, it implements the above-described vehicle control method.

[0103] According to the embodiments of this application, by executing the above-described vehicle control method, the vehicle can effectively suppress vibration and noise during gear shifting, thereby improving the smoothness and comfort of driving the vehicle.

[0104] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0105] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0106] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0107] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0108] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0109] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A vehicle control method, characterized in that, The vehicle includes a first power source and a second power source, and the method includes: If the vehicle meets the preset shift conditions, and there is a torque request, then the total required torque is determined based on the torque request. The first power source is controlled to output torque based on a target pre-torque value, which is used to eliminate gear backlash in the transmission system of the first power source. When the output torque of the first power source reaches the target pre-torque value, the first power source is controlled to respond to the torque request. The second power source is controlled to output torque based on the total required torque.

2. The vehicle control method according to claim 1, characterized in that, The control of the first power source to output torque based on the target pre-torque includes: The output torque of the first power source is controlled to change at a preset rate to the target pre-torque value. The preset rate is determined based on the rotational speed of the first power source, and the preset rate is negatively correlated with the rotational speed.

3. The vehicle control method according to claim 1, characterized in that, The target pre-torque value is determined in the following way: Obtain the current speed of the vehicle; The target pre-torque value is determined based on the vehicle speed and a preset mapping relationship, wherein the preset mapping relationship is used to indicate the correspondence between the vehicle speed and the target pre-torque value.

4. The vehicle control method according to claim 1, characterized in that, The step of determining that the vehicle meets the preset shift conditions includes: Obtain information on vehicle gear changes, drive mode, and vehicle speed; When the vehicle speed is greater than a preset vehicle speed threshold, the current gear changes in reverse based on the gear change information, and the driving mode is the target driving mode, the vehicle is determined to meet the preset shifting conditions. The reverse change indicates a shift from forward gear to reverse gear or vice versa, and the target driving mode is an electric four-wheel drive mode.

5. The vehicle control method according to claim 2, characterized in that, The method further includes: During the process of the output torque of the first power source changing to the target pre-torque at the preset rate, the first power source is controlled not to respond to the torque request.

6. The vehicle control method according to claim 5, characterized in that, The method further includes: Before the output torque of the first power source changes at the preset rate, the output torque of the first power source is controlled to a torque limit value, which is the minimum value between the absolute value of the requested torque of the first power source and the absolute value of the actual torque of the first power source.

7. The vehicle control method according to claim 4, characterized in that, The method further includes: When the output torque of the first power source reaches the target pre-torque value or the driving mode is not the target driving mode, the first power source is controlled to respond to the torque request.

8. The vehicle control method according to claim 7, characterized in that, The method further includes: If the absolute value of the difference between the output torque and the target pre-torque is less than a preset difference threshold, it is determined that the output torque of the first power source has reached the target pre-torque.

9. The vehicle control method according to claim 7, characterized in that, Controlling the first power source to respond to the torque request includes: The first output torque of the first power source and the second output torque of the second power source are determined based on the total required torque and the preset torque distribution relationship. The first power source is controlled to output torque based on the first output torque, and the second power source is controlled to output torque based on the second output torque, wherein the sum of the first output torque and the second output torque is the total required torque.

10. A vehicle, characterized in that, include: A memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the vehicle control method according to any one of claims 1-9.

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