Torque intervention-based four-wheel slip working condition reference vehicle speed acquisition method and system

Abstract

The present application belongs to the field of vehicle power control technology, and provides a four-wheel slip working condition reference vehicle speed acquisition method and system based on torque intervention, which comprises the following steps: real-time monitoring of the slip rate of each drive wheel of the vehicle; when the slip rate of the drive wheel exceeds a first threshold value and the duration exceeds a preset time, it is determined that the vehicle enters a four-wheel simultaneous slip state; after determining that the four-wheel simultaneous slip state is entered, the driving torque of the rear axle is decreased to zero at a gradient; during the driving torque decrease process of the rear axle and after the driving torque of the rear axle is decreased to zero, the slip rate of the rear axle is continuously monitored; when the slip rate of the rear axle is decreased and stabilized at a second threshold value which is lower than the first threshold value, it is determined that the rear axle speed signal recovery is reliable; and the reference vehicle speed of the vehicle is corrected based on the reliable rear axle speed. The present application actively intervenes in the driving torque, accurately recovers the calculation of the reference vehicle speed in the four-wheel slip working condition where the traditional method fails, and provides a correct decision basis for the whole vehicle power control.

Description

Technical Field

[0001] This invention belongs to the field of vehicle power control technology, and specifically relates to a method and system for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention. Background Technology

[0002] Reference speed is a key state variable in vehicle dynamics control systems. It is the basis for calculating wheel slip ratio and judging vehicle status, and is essential for the normal operation of systems such as ABS, TCS, and ESC.

[0003] When all four drive wheels of a vehicle slip simultaneously, the existing reference speed calculation logic becomes completely ineffective, affecting the normal operation of the control system.

[0004] Currently, the industry typically uses three methods to obtain reference vehicle speed: non-driving wheel speed, maximum wheel speed, and estimation algorithms based on vehicle dynamics models.

[0005] The above solution has obvious defects when all four wheels slip simultaneously. First, the slip ratio calculation is distorted, leading to incorrect judgment and intervention by the drive anti-slip control system. Second, systems such as TCS and ESP are forced to downgrade or exit, reducing vehicle safety. Third, there is a lack of effective recovery mechanism, which can only passively wait or adopt conservative strategies, resulting in low recovery efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention, so as to solve the problems of inaccurate calculation and untimely vehicle system recovery in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention, including: The slip ratio of each drive wheel of the vehicle is monitored in real time. When the slip ratio of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. After determining that all four wheels are slipping simultaneously, the drive torque of the rear axle is gradually reduced to zero. During the process of the rear axle drive torque decreasing and after it returns to zero, the slip ratio of the rear axle wheels is continuously monitored. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to be reliable after recovery. The vehicle's reference speed is corrected based on the restored reliable rear axle wheel speed.

[0008] Furthermore, the real-time monitoring of the slip ratio of each drive wheel of the vehicle includes: The system acquires real-time wheel speed sensor signals for each drive wheel, along with the current reference vehicle speed estimated by the vehicle control system, and calculates the result using a formula. x100% The slip ratio value is obtained as a percentage.

[0009] Furthermore, the step of determining that the vehicle has entered a state of simultaneous slippage of all four wheels when the slip ratio of the drive wheels exceeds a first threshold and the duration exceeds a preset time includes: Based on the slip ratio value, the slip ratio of the two drive wheels is continuously compared with the set first threshold. When the slip ratio of the two drive wheels exceeds the first threshold at the same time, a timer is started. If this state continues uninterrupted until the accumulated time of the timer exceeds the preset time T1, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels.

[0010] Furthermore, the step of reducing the drive torque of the rear axle to zero in a gradient manner after determining that all four wheels are slipping simultaneously includes: After determining that the vehicle has entered a state of simultaneous slippage of all four wheels, a control command is sent to the drive motor controller to initiate the rear axle torque zeroing program. The rear axle torque zeroing program controls the drive torque to decrease according to a preset gradient, specifically including: a preset fixed time period and a reduction in torque in each period. Then, at the end of each time period, the motor controller is instructed to reduce the output torque by a fixed amount, gradually decreasing periodically until the rear axle drive torque drops to zero. Throughout the entire descent process, the actual torque feedback is continuously monitored to ensure that the torque decreases smoothly to the target value according to the set gradient and rhythm.

[0011] Furthermore, during and after the decrease in rear axle drive torque, the slip ratio of the rear axle wheels is continuously monitored. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to have recovered reliably, including: The system continuously collects speed sensor signals from the two rear wheels and simultaneously obtains the currently estimated reference vehicle speed, and calculates the slip ratio of the two rear wheels in real time. The calculated slip ratio of each rear wheel is compared with a preset second threshold. When the slip ratio of both rear wheels drops below the second threshold, a timer is started. If the slip ratio of both rear wheels remains below the second threshold for a continuous period of time, it is determined that the rear axle wheel speed signal has recovered to a stable adhesion state. This wheel speed signal is reliable and can represent the real vehicle speed.

[0012] Furthermore, the correction of the vehicle's reference speed based on the recovered reliable rear axle wheel speed includes: First, obtain the wheel speeds of the two rear wheels deemed reliable, and take their average as the reliable vehicle speed value. Then, stop using the previously distorted reference speed and initiate a smooth transition procedure. Within each cycle, use a first-order low-pass filter or ramp function to gradually approximate the original reference speed value towards the reliable rear axle wheel speed value, using the following formula: The new reference vehicle speed is calculated iteratively as follows: α × previous cycle new reference vehicle speed + β × current reliable rear axle wheel speed. β is a filter coefficient used to control the speed at which new data is incorporated; the larger the coefficient, the faster the correction. α is the weighting coefficient of the estimated value from the previous control cycle, used to indicate the degree to which historical reference vehicle speed values ​​are retained. The sum of the filter coefficient and the weighting coefficient is 1, and the specific value is adjusted according to the vehicle's dynamic characteristics and the response requirements of the control system. This process continues until the error between the reference vehicle speed variable and the reliable rear axle wheel speed is less than the preset tolerance. At this point, the correction is considered complete, and the corrected reference vehicle speed is used directly thereafter.

[0013] Furthermore, after the reference vehicle speed is successfully corrected, the rear axle torque zeroing strategy is exited, allowing the drive torque to resume normal output according to the driver's request or the instructions of the upper control system.

[0014] Secondly, the present invention provides a four-wheel slippage condition reference vehicle speed acquisition system based on torque intervention, comprising: The slippage state judgment module is used to monitor the slippage rate of each drive wheel of the vehicle in real time. When the slippage rate of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. The torque control module is used to gradually reduce the drive torque of the rear axle to zero after determining that all four wheels are slipping simultaneously. The reliability determination module is used to continuously monitor the slip ratio of the rear axle wheels during the process of the rear axle drive torque decreasing and after it returns to zero. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to be reliable. The correction output module is used to correct the vehicle's reference speed based on the recovered reliable rear axle wheel speed.

[0015] Thirdly, the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention.

[0016] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention.

[0017] Compared with the prior art, the present invention has the following technical effects: This invention claims protection for a method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention. When the vehicle is detected to be in a state where all four wheels are slipping simultaneously, the method actively executes an intervention action to reduce the rear axle drive torque gradient to zero, forcing the drive wheels to disengage from the slippage state and restore road surface adhesion, thereby artificially creating a reliable vehicle speed signal source. Based on this, the reliable signal is then used to correct the overall vehicle reference speed.

[0018] Compared with the prior art solutions mentioned in the background section that rely on non-driving wheel speed, maximum wheel speed, or model estimation, this invention solves the fundamental defects of the prior art under extreme working conditions. Through active torque control, it can re-establish an accurate vehicle speed reference benchmark when traditional methods completely fail. This provides a continuous and accurate working basis for the vehicle's traction control system, electronic stability system, etc., under extreme working conditions such as rapid acceleration on low-friction surfaces. It effectively avoids system function degradation or shutdown caused by signal distortion, thereby significantly improving the vehicle's dynamic control capability and safety under extreme conditions.

[0019] This invention clarifies the specific calculation method for slip ratio, ensuring the feasibility of the technical solution and the accuracy of the judgment basis.

[0020] This invention further defines the conditions for determining that a vehicle has entered a state of simultaneous four-wheel slippage by introducing a timer and duration judgment. This improves the accuracy of state judgment and anti-interference ability, avoids false triggering caused by brief wheel slippage or signal jumps, and enhances the robustness of the system.

[0021] This invention specifically defines a gradient implementation method for torque reduction, namely, through periodic, fixed-amount decreases. This control method is beneficial for achieving a smooth, linear decrease in torque, avoiding the impact on the drive system and vehicle longitudinal dynamics caused by sudden changes in torque command, and balancing control effectiveness with ride comfort.

[0022] This invention sets clear conditions for determining the reliability of the rear axle wheel speed signal recovery, requiring that the slip ratios of both rear wheels be below a threshold and remain stable for a period of time. This ensures that the acquired "reliable wheel speed" is a true reflection of a stable adhesion state, rather than an instantaneous fluctuation, thus improving the reliability of the vehicle speed signal used for correction.

[0023] This invention discloses a correction algorithm for reference vehicle speed, employing a first-order low-pass filter or a similar smoothing function for transition. This method helps the reference vehicle speed converge smoothly and without abrupt changes from the distorted value to the true value, preventing the correction process itself from causing secondary interference to other control systems that depend on the reference vehicle speed, thus ensuring the overall smoothness of vehicle control.

[0024] This invention also protects a system that protects the implementation entity of the technical solution at the device level, clarifies the division and cooperation relationship of each functional module, and provides a system-level protection basis for deploying the software function in the vehicle controller. Attached Figure Description

[0025] Figure 1 This is a flowchart of the present invention.

[0026] Figure 2 This is a system structure diagram of the present invention. Detailed Implementation

[0027] Explanation of relevant parameters: ABS: Anti-lock Braking System TCS: Traction Control System ESC: Electronic Stability Control ESP: Electronic Stability Program The present invention will be further described below with reference to the accompanying drawings: Reference speed is the core state variable of the vehicle dynamics control system. It is also the basic prerequisite for accurately calculating wheel slip ratio and accurately judging the real-time driving status of the vehicle. It is directly related to whether the vehicle active safety control system such as ABS, TCS, and ESC can operate normally and reliably.

[0028] When a vehicle experiences rapid acceleration on a low-traction surface and all four drive wheels slip simultaneously, the existing reference speed calculation logic will completely fail, causing the vehicle's active safety control system to malfunction.

[0029] Currently, there are three main types of conventional technical methods in the industry for obtaining reference vehicle speed: using the speed of non-driving wheels as a reference, selecting the maximum wheel speed as a reference, and estimating using estimation algorithms based on vehicle dynamics models.

[0030] The aforementioned traditional solutions have significant technical flaws in scenarios where all four wheels slip simultaneously. First, the distortion of the reference vehicle speed leads to errors in the slip ratio calculation, causing the drive anti-slip control system to fail to accurately identify the slip state and even make incorrect control interventions. Second, it causes control systems such as TCS and ESP, which rely on the reference vehicle speed, to experience functional degradation or even shut down, significantly reducing the vehicle's driving stability and safety. At the same time, existing technologies lack efficient and targeted recovery mechanisms, and can only passively wait for the wheels to regain traction naturally or adopt a conservative torque reduction strategy, resulting in a slow vehicle traction recovery process and extremely low overall control efficiency.

[0031] For example, a rear-wheel-drive sedan starts at full throttle on a frozen lake. Due to the extremely low coefficient of friction on the ice, all four wheels (two drive wheels and two driven wheels spinning freely due to the vehicle's slippage) quickly enter a high-speed slippage state. At this time, the vehicle's electronic stability system uses the wheel speed of the non-drive wheels (front wheels) or the highest wheel speed among the four wheels as the reference speed. Since the front wheels have also completely lost traction and are spinning freely, their wheel speed is much higher than the vehicle's actual longitudinal speed (possibly close to 0 km / h), causing the reference speed calculated by the system to be severely inflated. Based on this incorrect reference speed, the drive wheel slip ratio calculated (formula: (wheel speed - reference speed) / reference speed) will be much lower than the actual value. This causes the traction control system (TCS) to misjudge that the wheel slippage is not severe, thus delaying intervention or only applying slight braking, failing to effectively suppress power waste and the tendency for the vehicle to lose control, resulting in the vehicle continuing to slip in place and failing to start effectively.

[0032] Example 1, please refer to Figure 1 Based on this, the present invention provides a method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention, including: The slip ratio of each drive wheel of the vehicle is monitored in real time. When the slip ratio of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. After determining that all four wheels are slipping simultaneously, the drive torque of the rear axle is gradually reduced to zero. During the process of the rear axle drive torque decreasing and after it returns to zero, the slip ratio of the rear axle wheels is continuously monitored. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to be reliable after recovery. The vehicle's reference speed is corrected based on the restored reliable rear axle wheel speed.

[0033] When this invention detects that a vehicle is slipping on all four wheels simultaneously, it actively executes a rear axle drive torque gradient reduction to zero, forcing the drive wheels to disengage from the slippage and regain road grip, thereby artificially creating a reliable vehicle speed signal source. Based on this reliable signal, the overall vehicle reference speed is then corrected.

[0034] Example 2: This invention provides a method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention, including: S1, monitors the slip rate of each drive wheel of the vehicle in real time. When the slip rate of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. The system acquires wheel speed sensor signals for each drive wheel in real time, and combines them with an initial estimated reference vehicle speed or a value from non-drive wheels or historical data. The slip ratio of each drive wheel is then calculated using the formula (wheel speed - reference vehicle speed) / reference vehicle speed × 100%.

[0035] Threshold comparison and continuous judgment: A relatively high first threshold is set, such as 15%-30%, to distinguish between normal acceleration slip and severe slip. The pre-judgment state is only entered when the slip ratio of all drive wheels exceeds this threshold simultaneously.

[0036] A preset time T1, such as a timer of 0.5-2 seconds, is introduced. Only when the high slip ratio continues for more than T1 is it finally determined that all four wheels are slipping simultaneously. This effectively filters out instantaneous fluctuations in wheel speed caused by brief road bumps or slight driver operations, prevents the system from being falsely triggered, and ensures the robustness of the judgment.

[0037] S2, after determining that all four wheels are slipping simultaneously, gradually reduces the drive torque of the rear axle to zero. Reducing the rear axle drive torque to zero is crucial because in four-wheel drive or rear-wheel drive vehicles, the rear axle is typically the primary drive source, making intervention on it the most direct. A gradient descent technique is employed, controlling the torque to decrease at a gradual rate, for example, reducing the maximum torque by 10%-20% every 100 milliseconds until it reaches 0 Nm. This avoids sudden torque changes that could cause strong jerking or impacts on driving smoothness and even vehicle stability, demonstrating a balance between driving comfort and safety.

[0038] The instruction is issued by the vehicle controller and executed by the motor controller or engine management system, forming a closed-loop torque control link.

[0039] S3, during the process of the rear axle drive torque decreasing and after it returns to zero, continuously monitor the slip ratio of the rear axle wheels. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, it is determined that the rear axle wheel speed signal has been restored reliably. The slip ratio of the rear axle wheels is continuously monitored, and a second threshold is set. This threshold, for example, 5%, is significantly lower than the first threshold in step S1, indicating that the wheels have recovered to a low-slip state with good adhesion. It is required that the slip ratio of the rear axle wheels not only decreases below the second threshold but also remains stable below it. This typically means that the system monitors this low-slip state for a short period to ensure that the wheel speed signal is stable and reliable, rather than fluctuating randomly.

[0040] Once the above conditions are met, the rear axle wheel speed signal can be determined, either individually or by averaging, to re-represent the vehicle's true longitudinal speed. This step serves as a bridge between torque intervention and vehicle speed correction, ensuring that the data source upon which subsequent corrections are based is valid.

[0041] S4 corrects the vehicle's reference speed based on the restored reliable rear axle wheel speed.

[0042] Use the recovered reliable signal to correct the distorted critical state variables in the system.

[0043] The reliable rear axle wheel speed (usually the average of the two wheel speeds to compensate for unilateral errors) is determined and used as an estimate of the true vehicle speed. A first-order low-pass filter or ramp function is used for smooth transition. For example, the formula is: New reference vehicle speed (k) = α × Old reference vehicle speed (k-1) + β × Current reliable rear axle wheel speed. Here, α and β are weighting coefficients (α+β=1), and the value of β determines the speed at which new data is incorporated.

[0044] This smoothing process effectively avoids abrupt changes in the reference vehicle speed value, preventing downstream control systems such as ESP and TCS from misjudging or violently maneuvering due to sudden changes in the vehicle speed signal, thus ensuring the smoothness and stability of the entire vehicle dynamics control process. After the correction is completed, the system regains an accurate reference vehicle speed, and all control systems can resume normal operation.

[0045] After the reference vehicle speed is successfully corrected, the system exits the rear axle torque zeroing strategy, allowing the drive torque to resume normal output according to the driver's request or the instructions of the upper control system.

[0046] This invention addresses the problem of all drive wheels slipping simultaneously and causing the reference speed calculation to completely fail when four-wheel drive vehicles accelerate rapidly on low-traction surfaces, and proposes an active intervention solution.

[0047] By monitoring the slip state of the drive wheels in real time, once it is determined that four-wheel slippage has occurred, the rear axle drive torque is actively and gradually reduced to zero in a controlled manner, forcing the rear wheels to regain effective adhesion to the road surface. This allows a reliable wheel speed signal that can represent the true vehicle speed to be obtained again, and this signal is used to smoothly correct the distorted system reference vehicle speed.

[0048] First, it transforms passive waiting into active recovery, enabling rapid reconstruction of accurate reference speed under extreme conditions, laying the foundation for the continuous and effective operation of control systems such as TCS and ESP. Second, through gradient torque reduction and smooth correction strategies, it greatly mitigates vehicle impact and speed jumps while restoring control functions, balancing functionality and driving comfort. Finally, the solution has clear logic and can be implemented entirely based on existing vehicle sensors and controllers without adding any hardware, possessing high engineering practical value.

[0049] One specific implementation method in the real-time monitoring and status judgment step is as follows: The system continuously collects signals from each wheel speed sensor and estimates a current reference vehicle speed based on the wheel speed of non-drive wheels or the historical maximum wheel speed. Then, it calculates the slip ratio of each drive wheel using the formula (drive wheel speed - reference vehicle speed) / reference vehicle speed × 100%. When the slip ratio of all drive wheels simultaneously exceeds a high threshold (e.g., 20%), a timer is started. If this state continues uninterrupted for a preset duration (e.g., 1 second), it is ultimately determined that the system has entered a state of simultaneous four-wheel slippage. The advantage of this method is that, through the dual judgment conditions of a high threshold and duration, it can effectively filter abnormal fluctuations in wheel speed caused by instantaneous road impacts or brief, violent driver operations, thereby accurately identifying truly continuous four-wheel slippage conditions, avoiding false system triggers, and ensuring the accuracy of control intervention.

[0050] Specifically, in activating the torque zeroing step, a feasible implementation method is as follows: After determining the slippage state, the vehicle controller sends a specific command to the drive motor controller to initiate the rear axle torque zeroing program. This program presets a fixed control cycle (e.g., 10ms) and a torque reduction amount within each cycle (e.g., 5% of the maximum torque). Subsequently, at the end of each control cycle, the motor controller is instructed to reduce its output torque by a fixed value, thus gradually decreasing periodically until the torque reaches zero. During this process, the system continuously monitors the actual output torque of the motor through bus feedback to ensure that it decreases according to the preset trajectory. By periodically decreasing in small steps, a smooth and linear decrease in drive torque is achieved, avoiding sudden torque interruption. This prevents vehicle jerking, transmission system shock, or vehicle instability that may result from a sudden drop in power, ensuring driving smoothness and comfort while restoring control function.

[0051] Optionally, in the wheel speed signal recovery step, one implementation is as follows: During the decrease in rear axle torque, the system continuously calculates the slip ratio of the two rear wheels. A second threshold (e.g., 5%), significantly lower than the slip determination threshold, is set as a reliable criterion for wheel speed recovery. When the slip ratio of both rear wheels drops below this threshold, a stabilization timer is started. If, for a subsequent continuous period (e.g., 200 milliseconds), the slip ratio of both rear wheels remains below this threshold, it is determined that the rear wheels have regained stable adhesion. Using a stricter low slip ratio threshold and stabilization time requirement ensures that the rear wheels have truly regained effective adhesion, and their wheel speed signals are stable and reliable, rather than fluctuating at the critical state between adhesion and slip. This provides a high-quality, reliable data source for subsequent reference speed correction, avoiding secondary errors that may arise from corrections based on unstable signals.

[0052] Furthermore, in the step of correcting the reference vehicle speed, a preferred implementation is as follows: First, the average of two reliable rear wheel speeds is taken as the baseline true vehicle speed. Then, the system stops using the old distorted reference vehicle speed and initiates a smooth transition algorithm, such as using a first-order low-pass filter, with the iterative formula: New reference vehicle speed = α × previous cycle new reference vehicle speed + β × current reliable rear axle wheel speed average. By appropriately setting the filter coefficient β (e.g., 0.2), the new reference vehicle speed value converges to the true vehicle speed value smoothly and gradually. This process continues until the error between the two is less than a preset tolerance. Smoothing the reference vehicle speed through the filtering algorithm avoids the numerical jumps caused by directly assigning the true wheel speed value to the system reference vehicle speed. Such jumps would be perceived as abnormal vehicle acceleration or deceleration by downstream controllers such as ESP and ABS, potentially triggering unnecessary control intervention or oscillations. The smooth transition ensures continuous and stable changes in the control system's state variables, guaranteeing a smooth transition throughout the entire vehicle dynamics control process.

[0053] In the embodiments of this application, after the reference vehicle speed correction is completed, the system immediately exits the rear axle torque zeroing restriction strategy, allowing the drive torque to resume normal output according to the driver's accelerator pedal request or the needs of the upper traction control system. Once the core state of the reference vehicle speed is corrected, the TCS and other systems restore their normal judgment and control basis. At this time, removing the torque restriction allows the vehicle's power to quickly respond to the driver's intention and restore normal driving status as soon as possible, thereby minimizing the impact of this method on vehicle power and driving experience, and achieving a seamless switch from abnormal condition handling to normal driving.

[0054] Example 3: This invention provides a method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention, including: S101 Continuous Monitoring: The system continuously receives signals from four wheel speed sensors and calculates an initial reference vehicle speed V based on existing algorithms (such as those based on the front wheels or maximum wheel speed).ref_init .

[0055] S102 Four-wheel slippage detection: Calculate the slip ratio of all wheels. Set the first threshold to 20% and the time threshold T1 to 1 second. When the system detects that the slip ratio of the two rear drive wheels is continuously greater than 20%, and the two front wheels (although they are not drive wheels, their calculated slip ratio is also greater than 20% due to the overall vehicle slippage) also exhibit a high slip ratio for more than 1 second, it is determined that all four wheels are slipping simultaneously, and proceed to step S103.

[0056] S103 activation: The system sends a command to the motor controller, requesting that the rear axle drive torque be gradually reduced from the current value at a gradient of 50 Nm every 100ms.

[0057] S104 Torque Reduction and Monitoring: Torque decreases as instructed. Simultaneously, the system continuously monitors the slip ratio of the two rear axle wheels.

[0058] S105 Rear Axle Recovery Judgment: A second threshold is set at 5%. When the slip ratio of the rear axle wheels decreases and stabilizes below 5%, the rear wheels are considered to have regained traction, and their wheel speed V... rear_valid It is credible, proceed to step S106.

[0059] S106 Reference Speed ​​Correction: System deactivates V ref_init This initiates a smooth transition process. For example, using a first-order filter: V ref_new (k) = 0.9 × V ref_new (k 1)+0.1×V rear_valid The reference vehicle speed is gradually converged to the actual rear axle wheel speed.

[0060] S107 Exit and Resume: When the corrected reference vehicle speed V ref_new With V rear_valid When the error is less than the set value, the correction is considered complete. The system then removes the zero-torque limit for the rear axle, and the drive torque returns to normal output. Control systems such as TCS are based on accurate V... ref_new Continue working.

[0061] Example 4 uses a rear-wheel-drive electric vehicle equipped with an electric motor-driven rear axle and a TCS / ESP system as the implementation example. The vehicle is started at full throttle on a low-traction surface covered with a thin layer of ice, causing all four wheels to slip simultaneously. The operation proceeds as follows: S1: Real-time monitoring and assessment of four-wheel slippage status The vehicle controller continuously collects wheel speed sensor signals from all four wheels: left front wheel speed V FL Right front wheel speed V FR Left rear wheel speed VRL Right rear wheel speed V RR At the same time, an initial reference vehicle speed V is estimated based on existing logic. _ref_est Let's assume the speed is 8 km / h at this point.

[0062] According to the formula x100% Real-time calculation of slip ratio for each wheel. The slip ratio λ of the left rear drive wheel is calculated. RL = 25%, slip ratio λ of the right rear drive wheel RR = 28%, and the slip ratio of both front wheels, calculated due to the overall vehicle slippage, is also greater than 20%.

[0063] Preset first threshold λ th1 = 20%, time threshold T1 = 1.0 second. The controller detected that the slip ratio of the two rear drive wheels (i.e., all drive wheels) continuously exceeded 20%, and this state was maintained for more than 1.0 second without interruption.

[0064] If the above conditions are met, the system determines that the vehicle has entered a state of "slipping of all four wheels at the same time" and triggers subsequent control.

[0065] S2: Activate rear axle torque zeroing strategy Upon determining that a slippage state has been entered, the vehicle control unit (VCU) immediately sends a control command to the motor controller (MCU) responsible for the rear axle.

[0066] Initiate the rear axle torque zeroing procedure. The command requires the current rear axle drive torque to be gradually reduced to 0 Nm at a preset gradient.

[0067] In this example, the gradient is set to decrease by 50 Nm every 100 milliseconds. After receiving the instruction, the MCU starts from the current output torque and decreases the torque instruction value by 50 Nm every 100ms, sequentially: 400Nm -> 350Nm -> 300Nm -> ... -> 50Nm -> 0Nm. This process takes a total of 800ms, achieving a slow decrease in torque and avoiding the shock of sudden power interruption.

[0068] S3: Rear Axle Wheel Speed ​​Reliability Recovery Monitoring During the decrease in rear axle torque and after it returns to zero, the system continuously monitors changes in rear axle wheel speed.

[0069] Continue calculating the slip ratios of the left and right rear wheels. As torque decreases, the degree of rear wheel slippage begins to lessen.

[0070] Recovery Decision: The system presets a second threshold λ th2= 5% (this value is far below the first threshold of 20%). When the slip rate of both the left and right rear wheels drops below 5% and remains stable for more than 0.3 seconds, the system determines that the rear wheels have regained stable adhesion.

[0071] At this time, the rear axle wheel speed V RL = 15 km / h, V RR = 15.2 km / h, which was deemed a reliable signal capable of characterizing the vehicle's true longitudinal speed. The system calculates the average speed V of the two wheels. _rear_valid = 15.1 km / h is taken as the reliable vehicle speed value.

[0072] S4: Reference vehicle speed corrected based on reliable wheel speed The system obtains reliable rear axle wheel speed V _rear_valid After reaching 15.1 km / h, a smooth correction process for the reference speed is initiated.

[0073] The system stops using the previously distorted estimate V. _ref_est (8 km / h) and start the first-order low-pass filter for data fusion.

[0074] Using the recursive formula V _ref_new (k) = 0.7 × V _ref_new (k-1) + 0.3 × V _rear_valid Perform iterative calculations. Where V _ref_new (k-1) is the correction value from the previous control cycle, with the initial value set to V. _ref_est β=0.3 is the filtering coefficient, which controls the speed at which new data (reliable rear axle wheel speed) is incorporated.

[0075] After several control cycles of iteration (e.g., 5 cycles, 10ms per cycle), V _ref_new The speed gradually converges smoothly and progressively from an initial 8 km / h to around 15.1 km / h. When the error between the two is less than 0.5 km / h, the correction is considered complete.

[0076] Once the reference vehicle speed correction is complete, the VCU immediately releases the output limit on the rear axle torque. Drive torque can then be restored to normal output based on driver accelerator pedal requests or adjustment commands from the TCS system. The entire vehicle dynamics control system (such as TCS and ESC) can then continue to operate effectively based on the accurate, corrected reference vehicle speed V_ref_new, restoring control over vehicle slippage.

[0077] In one embodiment of this application, such as Figure 2 As shown, a four-wheel slippage reference vehicle speed acquisition system based on torque intervention is provided, including: The slippage state judgment module is used to monitor the slippage rate of each drive wheel of the vehicle in real time. When the slippage rate of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. The torque control module is used to gradually reduce the drive torque of the rear axle to zero after determining that all four wheels are slipping simultaneously. The reliability determination module is used to continuously monitor the slip ratio of the rear axle wheels during the process of the rear axle drive torque decreasing and after it returns to zero. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to be reliable. The correction output module is used to correct the vehicle's reference speed based on the recovered reliable rear axle wheel speed.

[0078] The reference vehicle speed acquisition system provided by this invention, through continuous monitoring and accurate identification by the slippage state judgment module, can promptly diagnose the fundamental problem of reference speed failure when a four-wheel drive vehicle experiences severe slippage. The torque control module then performs core intervention, controlling the reduction of the rear axle drive torque gradient to zero, thus creating conditions for system recovery.

[0079] Building upon this foundation, the reliable judgment module precisely monitors the recovery of rear wheel slip, ensuring the accuracy and reliability of the captured rear axle wheel speed signal. Finally, the correction output module utilizes this reliable signal to smoothly correct and update the global reference vehicle speed. This enables the vehicle to quickly and proactively reconstruct an accurate speed reference even under extreme conditions such as rapid acceleration on low-traction surfaces where traditional methods fail. This ensures the continued effective operation of higher-level functions such as the electronic stability program and traction control system, significantly improving the vehicle's power and handling stability under extreme conditions.

[0080] The gradient torque reduction and smoothing filtering logic embedded in each module effectively avoids the impact of control actions and speed jumps, balancing functional implementation and driving smoothness. The entire system's closed-loop logic can be fully implemented using existing vehicle sensor and controller hardware and software resources, requiring no additional costs and demonstrating strong engineering practicality.

[0081] Specific limitations regarding the torque-intervention-based four-wheel slippage reference speed acquisition system can be found in the above-described limitations of the torque-intervention-based four-wheel slippage reference speed acquisition method; the corresponding technical effects are equivalent and will not be repeated here. Each module in the aforementioned torque-intervention-based four-wheel slippage reference speed acquisition system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, allowing the processor to call and execute the corresponding operations of each module.

[0082] The module division in this embodiment of the invention is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in the various embodiments of the invention can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0083] In another embodiment of the present invention, a computer device is provided, comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to achieve a corresponding method flow or corresponding function. The processor described in this embodiment of the present invention can be used in the operation of a method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention.

[0084] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention in the above embodiments.

[0085] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0087] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention, characterized in that, include: The slip ratio of each drive wheel of the vehicle is monitored in real time. When the slip ratio of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. After determining that all four wheels are slipping simultaneously, the drive torque of the rear axle is gradually reduced to zero. During the process of the rear axle drive torque decreasing and after it returns to zero, the slip ratio of the rear axle wheels is continuously monitored. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to be reliable after recovery. The vehicle's reference speed is corrected based on the restored reliable rear axle wheel speed.

2. The method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention according to claim 1, characterized in that, The real-time monitoring of the slip ratio of each drive wheel of the vehicle includes: The system acquires real-time wheel speed sensor signals for each drive wheel, along with the current reference vehicle speed estimated by the vehicle control system, and calculates the result using a formula. x100% The slip ratio value is obtained as a percentage.

3. The method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention according to claim 2, characterized in that, The determination that the vehicle has entered a state of simultaneous slippage of all four wheels when the slip ratio of the drive wheels exceeds a first threshold and the duration exceeds a preset time includes: Based on the slip ratio value, the slip ratio of the two drive wheels is continuously compared with the set first threshold. When the slip ratio of the two drive wheels exceeds the first threshold at the same time, a timer is started. If this state continues uninterrupted until the accumulated time of the timer exceeds the preset time T1, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels.

4. The method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention according to claim 1, characterized in that, After determining that all four wheels are slipping simultaneously, the method of gradually reducing the drive torque of the rear axle to zero includes: After determining that the vehicle has entered a state of simultaneous slippage of all four wheels, a control command is sent to the drive motor controller to initiate the rear axle torque zeroing program. The rear axle torque zeroing program controls the drive torque to decrease according to a preset gradient, specifically including: a preset fixed time period and a reduction in torque in each period. Then, at the end of each time period, the motor controller is instructed to reduce the output torque by a fixed amount, gradually decreasing periodically until the rear axle drive torque drops to zero. Throughout the entire descent process, the actual torque feedback is continuously monitored to ensure that the torque decreases smoothly to the target value according to the set gradient and rhythm.

5. The method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention according to claim 1, characterized in that, During and after the rear axle drive torque decreases and returns to zero, the slip ratio of the rear axle wheels is continuously monitored. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to have recovered reliably, including: The system continuously collects speed sensor signals from the two rear wheels and simultaneously obtains the currently estimated reference vehicle speed, and calculates the slip ratio of the two rear wheels in real time. The calculated slip ratio of each rear wheel is compared with a preset second threshold. When the slip ratio of both rear wheels drops below the second threshold, a timer is started. If the slip ratio of both rear wheels remains below the second threshold for a continuous period of time, it is determined that the rear axle wheel speed signal has recovered to a stable adhesion state. This wheel speed signal is reliable and can represent the real vehicle speed.

6. The method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention according to claim 1, characterized in that, The correction of the vehicle's reference speed based on the recovered reliable rear axle wheel speed includes: First, obtain the wheel speeds of the two rear wheels deemed reliable, and take their average as the reliable vehicle speed value. Then, stop using the previously distorted reference speed and initiate a smooth transition procedure. Within each cycle, use a first-order low-pass filter or ramp function to gradually approximate the original reference speed value towards the reliable rear axle wheel speed value, using the following formula: The new reference vehicle speed is calculated iteratively as follows: α × previous cycle new reference vehicle speed + β × current reliable rear axle wheel speed. β is a filter coefficient used to control the speed at which new data is incorporated; the larger the coefficient, the faster the correction. α is the weighting coefficient of the estimated value from the previous control cycle, used to indicate the degree to which historical reference vehicle speed values ​​are retained. The sum of the filter coefficient and the weighting coefficient is 1, and the specific value is adjusted according to the vehicle's dynamic characteristics and the response requirements of the control system. This process continues until the error between the reference vehicle speed variable and the reliable rear axle wheel speed is less than the preset tolerance. At this point, the correction is considered complete, and the corrected reference vehicle speed is used directly thereafter.

7. The method for obtaining reference vehicle speed under four-wheel slippage conditions based on torque intervention according to claim 6, characterized in that, After the reference vehicle speed is successfully corrected, the rear axle torque zeroing strategy is exited, allowing the drive torque to resume normal output according to the driver's request or the instructions of the upper control system.

8. A four-wheel slippage reference vehicle speed acquisition system based on torque intervention, characterized in that, include: The slippage state judgment module is used to monitor the slippage rate of each drive wheel of the vehicle in real time. When the slippage rate of the drive wheel exceeds the first threshold and the duration exceeds the preset time, it is determined that the vehicle has entered a state of simultaneous slippage of all four wheels. The torque control module is used to gradually reduce the drive torque of the rear axle to zero after determining that all four wheels are slipping simultaneously. The reliability determination module is used to continuously monitor the slip ratio of the rear axle wheels during the process of the rear axle drive torque decreasing and after it returns to zero. When the slip ratio of the rear axle wheels decreases and stabilizes at a second threshold below the first threshold, the rear axle wheel speed signal is determined to be reliable. The correction output module is used to correct the vehicle's reference speed based on the recovered reliable rear axle wheel speed.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for obtaining reference vehicle speed for four-wheel slippage conditions based on torque intervention as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for obtaining reference vehicle speed for four-wheel slippage conditions based on torque intervention as described in any one of claims 1 to 7.

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