A tire slip prevention stability system for a pure electric loader and a control method thereof

Abstract

The present application relates to the technical field of wheel vehicle control, and discloses a pure electric loader tire slip prevention stability system and a control method thereof. The present application aims to solve the technical problems of the existing wheel vehicle control technology, i.e. the reduction of the whole vehicle operation efficiency and the damage of the power transmission system mechanical life caused by the mismatch between the driving force output and the road adhesion limit under complex working conditions. The present application realizes the hierarchical determination of the slip state by real-time extraction of the wheel speed difference and its change rate characteristics, calculates the reduction coefficient of the nonlinear growth by using the slip deviation related torque adjustment gradient set, and executes the power directional reduction and gradual torque recovery logic. The method realizes the early intervention and dynamic suppression of the wheel speed divergence trend, reduces the idling amplitude of the driving wheel on the low adhesion road, reduces the abnormal loss of the tire and the transmission system, and guarantees the stability of the traction performance and the smoothness of the power switching of the loader in heavy load operation.

Description

Technical Field

[0001] This invention relates to the field of wheeled vehicle control technology, and more specifically, to a tire slippage prevention and stabilization system and control method for a pure electric loader. Background Technology

[0002] With the advancement of global energy transition and environmental protection policies, pure electric loaders, with electric motors as their core power source, have become an important development direction in the construction machinery field. In the field of wheeled vehicle control technology, existing drive control schemes mainly rely on the real-time scheduling of motor output torque by the vehicle controller. They manage power output by sensing pedal commands and basic vehicle status to meet the frequent starting, turning, and loading needs of loaders in off-road conditions.

[0003] However, during actual operation of loaders, due to frequent fluctuations in road surface adhesion conditions and instantaneous dynamic changes in the loading load, the drive wheels are prone to exceeding the ground adhesion limit and experiencing uncontrolled slippage when outputting large torque. This slippage not only leads to a significant loss of vehicle traction and reduces overall vehicle operating efficiency, but also causes severe abnormal tire wear and shortens the service life of transmission system components. How to accurately identify and effectively suppress tire slippage in complex and ever-changing off-road environments is a common technical challenge currently faced by wheeled electric drive construction machinery. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a tire slippage prevention and stability control method for pure electric loaders, which solves the technical problems of reduced overall vehicle operating efficiency and damaged mechanical life of power transmission system caused by the mismatch between driving force output and road surface adhesion limit in existing loaders under complex working conditions.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for preventing tire slippage and stabilizing a pure electric loader, which includes the following steps:

[0008] S1: Initialization: The vehicle controller loads control parameters, completes self-test of wheel speed sensors and communication links, and continuously monitors sensor signals and communication status;

[0009] S2: Data Acquisition and Status Determination: Acquire wheel speed signals and drive motor output torque, calculate the maximum wheel speed difference and rate of change based on the wheel speed signals, and determine the status of the loader based on the maximum wheel speed difference and the rate of change.

[0010] S3: Pre-slip state handling: When the loader is in a pre-slip state, the slip trend value is determined according to the rate of change, and the output torque is limited according to the slip trend value;

[0011] S4: Handling of slippage: When the loader is in a slippage state, the slippage level and torque adjustment amount are determined according to the maximum wheel speed difference. A warning is issued to the driver according to the slippage level, and the output torque is adjusted according to the torque adjustment amount until the slippage is eliminated. After the slippage is eliminated, the output torque is gradually restored to the value requested by the driver.

[0012] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the calibration process of the control parameters specifically includes: the control parameters include a slippage judgment threshold and a pre-slippage judgment threshold; the slippage judgment threshold is determined based on the critical maximum wheel speed difference when the loader slips, and the pre-slippage judgment threshold is determined based on the critical value of the rate of change of the maximum wheel speed difference during the process from normal driving to slippage.

[0013] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of continuously monitoring sensor signals and communication status specifically includes: monitoring the effectiveness of each wheel speed sensor signal and the stability of the communication link between the vehicle controller and the drive motor; if an abnormal transmission of a single wheel speed sensor signal is detected, using the wheel speed signal of the opposite wheel on the same axle as a reference value to calculate and generate a fault signal; if multiple abnormal transmissions of wheel speed sensor signals are detected, stopping the anti-slippage control function and generating a fault signal; and issuing a warning to the driver based on the fault signal.

[0014] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of calculating the maximum wheel speed difference and its rate of change specifically includes: collecting wheel speed signals at fixed intervals, comparing the maximum wheel speed value and the minimum wheel speed value of the current period, and subtracting them to obtain the maximum wheel speed difference of the current period; subtracting the maximum wheel speed difference of the previous period from the maximum wheel speed difference of the current period, and then dividing by the sampling period to obtain the rate of change.

[0015] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of determining the state of the loader specifically includes: the state of the loader includes a non-slippage state, a pre-slippage state, and a slippage state; when the maximum wheel speed difference is less than the slippage determination threshold and the rate of change is less than the pre-slippage determination threshold, the loader is determined to be in a non-slippage state, and no intervention operation is performed; when the maximum wheel speed difference is less than the slippage determination threshold but the rate of change is greater than the pre-slippage determination threshold, the loader is determined to be in a pre-slippage state; when the maximum wheel speed difference is greater than the slippage determination threshold, the loader is determined to be in a slippage state.

[0016] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of determining the slippage trend value specifically includes: normalizing the rate of change to obtain the slippage trend value; establishing a mapping relationship between the slippage trend value and the output torque limiting strength, wherein the slippage trend value represents the current slippage risk level, and the larger the slippage trend value, the greater the corresponding limiting strength of the output torque.

[0017] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of limiting the output torque specifically includes: calibrating the maximum allowable torque increase rate based on the power output characteristics of the drive motor and the mechanical strength of the transmission system; calculating the torque limit coefficient according to the slippage trend value, wherein the larger the slippage trend value, the smaller the torque limit coefficient; multiplying the maximum allowable torque increase rate by the torque limit coefficient to obtain a torque increase rate limit, and controlling the rate of change of the output torque of the drive motor not to exceed the torque increase rate limit.

[0018] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of determining the slippage level and torque adjustment amount specifically includes: calibrating a moderate slippage threshold and a severe slippage threshold based on the maximum wheel speed difference and in combination with the loader's power characteristics and ground adhesion characteristics, and constructing a slippage level including mild slippage, moderate slippage, and severe slippage; comparing the maximum wheel speed difference with each slippage threshold to determine the slippage level and issuing a warning of the corresponding level to the driver; determining a torque reduction coefficient based on the deviation ratio of the maximum wheel speed difference relative to the slippage judgment threshold; multiplying the current output torque by the torque reduction coefficient to obtain the torque adjustment amount, and controlling the output torque of the drive motor to subtract the torque adjustment amount.

[0019] As a preferred embodiment of the anti-tire slippage stability control method for a pure electric loader according to the present invention, the process of gradually restoring the output torque specifically includes: calculating the deviation between the output torque and the value requested by the driver; dynamically adjusting the torque recovery rate according to the deviation; establishing a positive correlation mapping relationship between the deviation and the torque recovery rate, so that the output torque gradually recovers to the value requested by the driver, preventing the torque recovery from being too fast and causing slippage again; if pre-slippage is detected again during the recovery process, the recovery is immediately stopped and the pre-slippage state is re-entered for processing.

[0020] The present invention also provides a tire slippage prevention and stabilization system for a pure electric loader, used to perform the above method, specifically including the following modules:

[0021] Parameter loading and self-test module: used for configuring and loading control parameters of the vehicle controller, and for self-testing and continuously monitoring the validity of the signals from each wheel speed sensor and the stability of the communication link;

[0022] Signal acquisition and calculation module: Real-time acquisition of wheel speed signals and current output torque of drive motor, and calculation of maximum wheel speed difference and maximum wheel speed difference change rate in the current cycle;

[0023] State determination logic module: Receives the calculation results of the signal acquisition and calculation module, and determines whether the loader is currently in a non-slipping state, a pre-slipping state, or a slipping state by comparing the maximum wheel speed difference and its rate of change with a preset threshold.

[0024] Pre-slip intervention module: Receives the pre-slip state command output by the state determination logic module, normalizes the rate of change to obtain a slip trend value, determines the torque limit coefficient based on the slip trend value, and then calculates the torque increase rate limit.

[0025] Slip control execution module: Receives slip status command output by the status determination logic module, determines the current slip level and determines the torque reduction coefficient according to the deviation ratio of the maximum wheel speed difference relative to the slip determination threshold, and eliminates slip by controlling the output torque to subtract the torque adjustment amount determined by the torque reduction coefficient;

[0026] Dynamic recovery control module: After slippage is eliminated, it calculates the torque recovery rate in real time based on the deviation between the current output torque and the driver's requested value, so that the output torque gradually recovers to the driver's requested value, and monitors the risk of slippage again during the recovery process;

[0027] Alarm prompt module: Receives the slippage level information output by the state determination logic module or the fault signal output by the parameter loading and self-test module, and issues a corresponding level of visual or auditory alarm prompt to the driver.

[0028] The beneficial effects of this invention are as follows: Real-time extraction of wheel speed difference and its rate of change characteristics enables graded determination of slippage state; the slippage deviation is used to correlate with the torque adjustment gradient set to calculate the reduction coefficient of nonlinear growth; and power-oriented reduction and progressive torque recovery logic are executed. This method achieves early intervention and dynamic suppression of wheel speed divergence trends, reduces the idling amplitude of the drive wheels on low-traction surfaces, reduces abnormal wear on tires and the transmission system, and ensures the stability of the traction performance and the smoothness of power switching of the loader during heavy-load operations. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of a tire slippage prevention and stability control method for a pure electric loader.

[0031] Figure 2 This is a flowchart of the wheel speed sensor self-test and fault tolerance processing.

[0032] Figure 3 This is a flowchart of the torque recovery process.

[0033] Figure 4 This is a flowchart of a tire slippage stabilization system module for a pure electric loader. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "example" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The appearance of an embodiment in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0037] Example 1

[0038] Reference Figures 1-3As one embodiment of the present invention, this embodiment provides a method for preventing tire slippage and stabilizing a pure electric loader, comprising the following steps:

[0039] S1. Initialization: The vehicle controller loads control parameters, completes self-test of wheel speed sensors and communication links, and continuously monitors sensor signals and communication status.

[0040] The calibration process of the control parameters specifically includes the following: the control parameters include the slippage judgment threshold and the pre-slippage judgment threshold; the slippage judgment threshold is determined based on the critical maximum wheel speed difference when the loader slips, and the pre-slippage judgment threshold is determined based on the critical value of the rate of change of the maximum wheel speed difference during the process from normal driving to slippage.

[0041] The process of continuously monitoring sensor signals and communication status specifically includes monitoring the effectiveness of each wheel speed sensor signal and the stability of the communication link between the vehicle controller and the drive motor; if an abnormal transmission of a single wheel speed sensor signal is detected, the wheel speed signal of the opposite wheel on the same axle is used as a reference value to calculate and generate a fault signal; if multiple abnormal transmissions of wheel speed sensor signals are detected, the anti-slip control function is stopped and a fault signal is generated; and a warning is issued to the driver based on the fault signal.

[0042] The vehicle control unit (VCU) reads control parameters from non-volatile memory (NVM). These parameters are empirical values ​​obtained through real-vehicle tests in various standard scenarios, such as dry cement roads, wet mud roads, and loose gravel roads. They reflect the loader's stress performance under different loads and road surface forces, forming a multi-dimensional reference benchmark and providing a data foundation for subsequent state determination.

[0043] By gradually increasing the motor output torque under different loads, the rotational speeds of each wheel are monitored and recorded in real time when the tires begin to spin freely and the overall vehicle traction shows a decreasing inflection point. The difference between the highest and lowest rotational speeds of the wheels is extracted as the critical maximum wheel speed difference. The steering behavior of the loader during actual operation will cause an inherent speed difference between the inner and outer wheels. To ensure control accuracy, a redundancy of 15% to 20% is generally added to this critical difference to avoid logical mis-triggers that may be caused by steering behavior, thereby obtaining the slippage judgment threshold.

[0044] By capturing the dynamic abrupt changes in wheel speed signals, the sudden acceleration of the wheel reflected by the rate of change of wheel speed can be identified. Under normal starting conditions, the wheel speed increases smoothly and linearly with the vehicle speed, and its rate of change remains in a low and stable range. However, when the tires are about to exceed the ground adhesion limit, the balance between the driving torque and the equal reaction force on the ground is broken, resulting in a step-like increase in wheel speed acceleration. By analyzing the characteristics of the drastic change in the slope of this abrupt change point on the wheel speed rate of change curve, the critical point of the rate of change of wheel speed at the transition from a stable rolling state to a slight slip state is extracted and used as the pre-slip judgment threshold. The determination of the pre-slip judgment threshold provides a basis for early control intervention, allowing intervention before the driver perceives slippage.

[0045] During continuous monitoring, a verification method based on local logic comparison is used to determine the effectiveness of sensors. When an abnormal level or signal freeze is detected in the raw data of a wheel speed sensor, the normal sensor signal on the opposite side of the coaxial wheel of the failed wheel is directly extracted and mapped to the calculated reference value of the currently failed side, while generating a fault alarm signal. If multiple wheel speed sensors fail, or if the heartbeat message between the vehicle controller and the drive motor controller (MCU) is lost, it is determined that the integrity of the current hardware link is compromised. At this time, the output logic of the anti-slip control function will be forcibly stopped to prevent erroneous intervention based on incorrect data, and a maintenance warning will be issued to the driver.

[0046] S2. Data Acquisition and Status Determination: Collect wheel speed signals and drive motor output torque, calculate the maximum wheel speed difference and rate of change based on the wheel speed signals, and determine the status of the loader based on the maximum wheel speed difference and the rate of change.

[0047] The process of calculating the maximum wheel speed difference and its rate of change specifically includes: collecting wheel speed signals at fixed intervals, comparing the maximum wheel speed value and the minimum wheel speed value of the current period, subtracting them to obtain the maximum wheel speed difference of the current period; subtracting the maximum wheel speed difference of the previous period from the maximum wheel speed difference of the current period, and then dividing by the sampling period to obtain the rate of change.

[0048] The process of determining the loader's status specifically includes three states: no slippage, pre-slippage, and slippage. When the maximum wheel speed difference is less than the slippage determination threshold and the rate of change is less than the pre-slippage determination threshold, the loader is determined to be in a no-slippage state, and no intervention operation is performed. When the maximum wheel speed difference is less than the slippage determination threshold but the rate of change is greater than the pre-slippage determination threshold, the loader is determined to be in a pre-slippage state. When the maximum wheel speed difference is greater than the slippage determination threshold, the loader is determined to be in a slippage state.

[0049] The data acquisition process involves acquiring raw pulse data from wheel speed sensors in real time via the Controller Area Network (CAN) bus interface and parsing it into wheel speed values ​​in standard units. The acquisition process follows a fixed sampling period, consistent with the underlying task scheduling period of the vehicle controller, ensuring standardized analysis and logical interoperability, and providing a stable time reference for subsequently constructing dynamically changing wheel speed characteristics. Within each sampling period, the wheel speed data of all wheels is traversed, identifying the wheel speed value with the largest and smallest values. The absolute difference between the two is calculated to obtain the maximum wheel speed difference for the current period. The calculation formula is as follows:

[0050]

[0051] in, Indicates the first The maximum wheel speed difference within each sampling period; This represents the highest wheel speed value obtained during the current cycle. This represents the lowest wheel speed value obtained during the current cycle.

[0052] By establishing logical connections between adjacent cycles, the dynamic trend of wheel speed divergence is captured. The rate of change at the current moment is calculated by subtracting the maximum wheel speed difference from the maximum wheel speed difference of the previous sampling cycle and dividing by the sampling period. The sampling period is precisely set to match the physical sampling frequency of the wheel speed sensor and the operational step size of the controller. This rate of change is an indicator for identifying latent slippage risk, reflecting the acceleration of wheel speed divergence. Its calculation formula is as follows:

[0053]

[0054] in, Indicates the first The maximum rate of change of wheel speed difference within each sampling period; Indicates the first The maximum wheel speed difference within each sampling period; This represents the maximum wheel speed difference recorded in the previous sampling period; This indicates the sampling period (the underlying task scheduling period of the vehicle controller).

[0055] Next, determining the loader's state requires first establishing a judgment environment consisting of the maximum wheel speed difference and the rate of change. Then, the dynamic data calculated in real time is compared with preset control parameters to determine the specific state of the loader at the current moment.

[0056] If the maximum wheel speed difference is within the slippage detection threshold and the rate of change does not exceed the pre-slippage detection threshold, the wheel is determined to be in a stable pure rolling or low-slip state, defined as a non-slip state. In this state, monitoring is maintained without physical intervention on the drive torque to ensure the normal power output of the loader.

[0057] The maximum wheel speed difference is within the slippage judgment threshold, but its rate of change fluctuates drastically and exceeds the pre-slippage judgment threshold. This indicates that the wheel speed is about to diverge explosively and is defined as a pre-slippage state. The core of this judgment lies in using the step characteristic of the rate of change to achieve early detection and lock the risk area before the wheel actually spins significantly.

[0058] If the maximum wheel speed difference exceeds the slippage threshold, regardless of the rate of change, the tire is determined to have lost its grip and balance with the ground, and is defined as slipping.

[0059] In summary, by utilizing the combined characteristics of the maximum wheel speed difference and its rate of change, a real-time status determination criterion based on the degree and trend of slippage is constructed. This criterion, through quantification and logical partitioning of physical signals, achieves accurate identification and classification of the loader's operating status, thus providing a solid data foundation for subsequent implementation of differentiated torque intervention logic based on different status affiliations.

[0060] S3. Pre-slip state handling: When the loader is in a pre-slip state, the slip trend value is determined according to the rate of change, and the output torque is limited according to the slip trend value.

[0061] The process of determining the slippage trend value specifically includes: normalizing the rate of change to obtain the slippage trend value; establishing a mapping relationship between the slippage trend value and the output torque limiting strength, whereby the slippage trend value represents the current slippage risk level, and the larger the slippage trend value, the greater the corresponding output torque limiting strength.

[0062] The process of limiting output torque specifically includes: calibrating the maximum allowable torque increase rate based on the power output characteristics of the drive motor and the mechanical strength of the transmission system; calculating the torque limit coefficient based on the slippage trend value, with a larger slippage trend value resulting in a smaller torque limit coefficient; multiplying the maximum allowable torque increase rate by the torque limit coefficient to obtain the torque increase rate limit, and controlling the rate of change of the drive motor output torque to not exceed the torque increase rate limit.

[0063] The process involves extracting the wheel speed difference change rate calculated in the current cycle after determining that the loader has entered a pre-slip state. To convert this into a standardized risk indicator, a pre-test is conducted on extremely low-traction surfaces such as ice or wet mud, recording the extreme acceleration trend at the moment the wheels lose traction. A maximum value for the change rate is then set as the termination reference point of the mapping interval, with the pre-slip judgment threshold as the starting reference point. By calculating the relative position of the change rate at the current moment within the interval formed by the aforementioned starting and termination reference points, it is mapped to a dimensionless numerical space between 0 and 1, thus generating a slippage trend value. This method transforms physical acceleration fluctuations into standardized values ​​that intuitively describe the degree to which the wheels deviate from their normal driving state. This not only eliminates the differences in raw data fluctuations under different road conditions but also ensures the stability of subsequent decision-making logic. A higher slippage trend value indicates a greater risk of the wheels entering a true slippage state. The slippage trend value is calculated as follows:

[0064]

[0065] in, This represents the dimensionless slippage trend value obtained after normalization, with a value range from 0 to 1; Indicates the first The maximum rate of change of wheel speed difference within each sampling period; This represents the preset pre-slip judgment threshold, which serves as the starting reference point for the mapping interval; This represents the preset maximum rate of change, which serves as the endpoint reference point for the mapping interval.

[0066] Next, to define the safe boundary of power output, the maximum allowable torque increase rate of the loader under the current hardware configuration was calibrated, taking into account the response characteristics of the drive motor under millisecond-level current switching and the structural strength of load-bearing components such as reducer gears and half-shafts in the transmission system under instantaneous alternating loads. This rate benchmark represents the limit of power increase that the drive chain can withstand without mechanical damage and while maintaining ground adhesion balance.

[0067] Subsequently, a mapping relationship between the slippage trend value and the output torque limitation strength is established. The magnitude of the slippage trend value characterizes the current slippage risk level, and the corresponding torque limitation coefficient is determined accordingly. This coefficient exhibits an inverse adjustment relationship with the slippage risk: when the slippage trend value is small, it indicates a low current slippage risk, and a larger coefficient is allocated to maintain a faster power response; conversely, when the slippage trend value continuously increases with the divergence of wheel speed acceleration, it indicates an increased slippage risk, and the allocated coefficient decreases rapidly, thereby achieving a dynamic increase in the output torque limitation strength. During this process, based on the power output characteristics of the drive motor and the mechanical strength of the transmission system, the maximum permissible torque increase rate is calibrated. Specifically, by analyzing the current response slope of the motor under different loads, and the fatigue strength of the reducer gears and half-shafts in the transmission chain under instantaneous alternating loads, the growth limit that the power transmission can withstand without causing mechanical damage and maintaining adhesion balance is defined. Finally, this maximum permissible torque increase rate is multiplied by the previously determined coefficient to obtain the torque increase rate limit at the current moment.

[0068] At the execution level, the vehicle controller sends the calculated torque increase rate limit to the drive motor controller, forcibly constraining the rate of increase of the motor's output torque over time. In this state, even if a large torque request is received from the accelerator pedal, the actual output torque of the motor will increase along a gradual, speed-limited trajectory by limiting the increment step of the commanded torque within the sampling period. Because the rate of increase in driving force is suppressed within the dynamic range that the ground adhesion can support in real time, the acceleration process of wheel speed divergence can be effectively blocked, thereby delaying or suppressing the tendency of slippage to the maximum extent at the physical level.

[0069] S4. Handling of slippage: When the loader is in a slippage state, the slippage level and torque adjustment amount are determined according to the maximum wheel speed difference. A warning is issued to the driver according to the slippage level, and the output torque is adjusted according to the torque adjustment amount until the slippage is eliminated. After the slippage is eliminated, the output torque is gradually restored to the value requested by the driver.

[0070] The process of determining the slippage level and torque adjustment amount specifically includes: calibrating moderate and severe slippage thresholds based on the maximum wheel speed difference and considering the loader's power characteristics and ground adhesion characteristics; constructing a slippage level system including mild, moderate, and severe slippage; comparing the maximum wheel speed difference with each slippage threshold to determine the slippage level and issuing a corresponding warning to the driver; determining the torque reduction coefficient based on the deviation ratio of the maximum wheel speed difference from the slippage judgment threshold; multiplying the current output torque by the torque reduction coefficient to obtain the torque adjustment amount; and controlling the output torque of the drive motor to subtract the torque adjustment amount.

[0071] The process of gradually restoring output torque specifically includes: calculating the deviation between the output torque and the value requested by the driver; dynamically adjusting the torque recovery rate based on the deviation; establishing a positive correlation between the deviation and the torque recovery rate to gradually restore the output torque to the value requested by the driver, preventing excessive torque recovery from causing slippage again; and immediately stopping the recovery and re-entering the pre-slippage state if pre-slippage is detected again during the recovery process.

[0072] Once the loader is determined to be slipping, tiered intervention is implemented based on the severity of wheel slippage. First, a slippage threshold is used as a baseline, combined with the torque output capability of the drive motor at the current speed and the tire adhesion limit on typical working surfaces, to determine the critical speed difference point where traction drops drastically. Through real-vehicle testing, the speed difference point where traction first shows a significant decline is calibrated as the moderate slippage threshold, and the speed difference point where the vehicle's traction is nearly lost and wheel speeds are completely divergent is calibrated as the severe slippage threshold, thus dividing the judgment range into progressively increasing levels from mild to moderate to severe. The real-time calculated maximum wheel speed difference is compared with these thresholds to identify the current level, and the instrument panel then issues a warning to the driver corresponding to the level through different colors or beep frequencies.

[0073] To determine the torque adjustment amount, real-vehicle calibration is first performed on various standard grip surfaces to obtain a set of characteristic data reflecting the mapping relationship between the wheel instability ratio and the degree of traction loss. This data is then used to construct a slippage deviation-related torque adjustment gradient set, which is stored in the non-volatile memory of the vehicle controller. The deviation ratio where the current maximum wheel speed difference exceeds the slippage threshold is calculated; this ratio directly reflects the multiple by which the wheel spin speed deviates from the safe baseline. Subsequently, using the deviation ratio as an index, the corresponding torque reduction coefficient is retrieved and determined from the slippage deviation-related torque adjustment gradient set. When the deviation ratio is small, the retrieved torque reduction coefficient is in a low-gain range for fine-tuning; however, when the deviation ratio increases rapidly due to severe slippage, the torque reduction coefficient increases dramatically with the deviation ratio. Then, the current actual output torque of the motor is multiplied by this reduction coefficient to calculate the specific torque adjustment amount. Finally, the vehicle controller sends a subtraction command to the motor controller, controlling the output torque of the drive motor to directly subtract this adjustment amount. This forced power reduction suppresses wheel spin, causing the tire speed to quickly return to a range where grip can be regained. The formula for calculating the deviation ratio is as follows:

[0074]

[0075] in, This indicates the percentage deviation of the current maximum wheel speed difference from the slippage detection threshold. Indicates the first The maximum wheel speed difference within each sampling period; This indicates the threshold for determining slippage.

[0076] Finally, the deviation between the current restricted output torque and the driver's requested value is calculated, and the torque recovery rate is adjusted in real time based on this deviation. In the initial recovery phase, due to the high deviation, a higher recovery rate is allocated to quickly compensate for the power shortfall. As the output torque approaches the driver's requested value, the deviation gradually decreases, and the recovery rate is adjusted accordingly. This gradual approach ensures a smooth power growth trajectory, characterized by initial rapid acceleration followed by slower acceleration, effectively preventing abrupt changes in wheel acceleration caused by excessively rapid torque recovery. If the pre-slip condition is detected again during recovery, recovery is immediately stopped, and the process returns to the pre-slip state handling steps.

[0077] Example 2

[0078] Reference Figure 4 These are two embodiments of the present invention. This embodiment provides a tire slippage stabilization system for a pure electric loader. The system is typically deployed on a high-performance computing server to execute the steps described in Embodiment 1.

[0079] The system's software architecture consists of a set of highly collaborative functional modules, specifically including:

[0080] Parameter loading and self-test module: used for configuring and loading control parameters of the vehicle controller, and for self-testing and continuously monitoring the validity of the signals from each wheel speed sensor and the stability of the communication link;

[0081] Signal acquisition and calculation module: Real-time acquisition of wheel speed signals and current output torque of drive motor, and calculation of maximum wheel speed difference and maximum wheel speed difference change rate in the current cycle;

[0082] State determination logic module: Receives the calculation results of the signal acquisition and calculation module, and determines whether the loader is currently in a non-slipping state, a pre-slipping state, or a slipping state by comparing the maximum wheel speed difference and its rate of change with a preset threshold.

[0083] Pre-slip intervention module: Receives the pre-slip state command output by the state determination logic module, normalizes the rate of change to obtain a slip trend value, determines the torque limit coefficient based on the slip trend value, and then calculates the torque increase rate limit.

[0084] Slip control execution module: Receives slip status command output by the status determination logic module, determines the current slip level and determines the torque reduction coefficient according to the deviation ratio of the maximum wheel speed difference relative to the slip determination threshold, and eliminates slip by controlling the output torque to subtract the torque adjustment amount determined by the torque reduction coefficient;

[0085] Dynamic recovery control module: After slippage is eliminated, it calculates the torque recovery rate in real time based on the deviation between the current output torque and the driver's requested value, so that the output torque gradually recovers to the driver's requested value, and monitors the risk of slippage again during the recovery process;

[0086] Alarm prompt module: Receives the slippage level information output by the state determination logic module or the fault signal output by the parameter loading and self-test module, and issues a corresponding level of visual or auditory alarm prompt to the driver.

[0087] During the system startup and operation phase, the parameter loading and self-test module first loads the control parameters and scans and monitors the validity of the signals from each wheel speed sensor and the stability of the communication link. If an abnormality is detected, the generated fault signal is transmitted to the alarm prompt module in real time.

[0088] During system operation, the signal acquisition and calculation module obtains the output torque of the drive motor and the wheel speed signals of each wheel, and calculates the current maximum wheel speed difference and rate of change in each sampling period. These calculation results are then sent to the state determination logic module, which determines the current state of the loader by comparing the received dynamic data with preset thresholds, i.e., whether it is in a non-slipping state, a pre-slipping state, or a slipping state.

[0089] If the determination result indicates a pre-slippage state, the pre-slippage intervention module will intervene. This module performs normalization processing on the received rate of change data to generate a slippage trend value, and determines the torque limit coefficient and torque increase rate limit accordingly, thereby constraining the torque increase slope of the drive motor.

[0090] If the judgment result indicates that the vehicle is slipping, the slip control execution module is activated. After determining the current slip level, this module first transmits the level information to the alarm prompt module to issue a corresponding alarm prompt to the driver; then, it determines the torque reduction coefficient by calculating the deviation ratio of the maximum wheel speed difference relative to the slip judgment threshold, and finally controls the output torque of the drive motor to subtract the torque adjustment amount determined by the coefficient, thereby suppressing wheel spin.

[0091] Once slippage is detected and eliminated, the dynamic recovery control module executes the torque recovery process. This module calculates the deviation between the received current output torque and the driver's requested value, and adjusts the torque recovery rate in real time accordingly, ensuring a smooth and gradual recovery of the output torque to the requested value. Simultaneously, the signal acquisition and calculation module continuously monitors wheel speed during the recovery period. If the pre-slippage determination condition is triggered again, the recovery procedure is immediately terminated, and a request is made to re-enter the pre-slippage intervention logic.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preventing tire slippage and stabilizing a pure electric loader, characterized in that, Performed by a computer device, including the following steps: S1: Initialization: The vehicle controller loads control parameters, completes self-test of wheel speed sensors and communication links, and continuously monitors sensor signals and communication status; S2: Data Acquisition and Status Determination: Acquire wheel speed signals and drive motor output torque, calculate the maximum wheel speed difference and rate of change based on the wheel speed signals, and determine the status of the loader based on the maximum wheel speed difference and the rate of change. S3: Pre-slip state handling: When the loader is in a pre-slip state, the slip trend value is determined according to the rate of change, and the output torque is limited according to the slip trend value; S4: Handling slippage: When the loader is in a slippage state, the slippage level and torque adjustment amount are determined according to the maximum wheel speed difference. A warning is issued to the driver according to the slippage level, and the output torque is adjusted according to the torque adjustment amount until the slippage is eliminated. After the slippage is eliminated, the output torque is gradually restored to the value requested by the driver. Specifically, the calibration process of the control parameters in step S1 includes: the control parameters include a slippage judgment threshold and a pre-slippage judgment threshold; the slippage judgment threshold is determined based on the critical maximum wheel speed difference when the loader slips, and the pre-slippage judgment threshold is determined based on the critical value of the rate of change of the maximum wheel speed difference during the process from normal driving to slippage. The process of calculating the maximum wheel speed difference and its rate of change in step S2 specifically includes: collecting wheel speed signals at fixed intervals, comparing the maximum wheel speed value and the minimum wheel speed value of the current period, and subtracting them to obtain the maximum wheel speed difference of the current period; subtracting the maximum wheel speed difference of the previous period from the maximum wheel speed difference of the current period, and then dividing by the sampling period to obtain the rate of change; The process of determining the loader's state in step S2 specifically includes: the loader's state includes a non-slipping state, a pre-slipping state, and a slipping state; when the maximum wheel speed difference is less than the slipping determination threshold and the rate of change is less than the pre-slipping determination threshold, the loader is determined to be in a non-slipping state, and no intervention operation is performed; when the maximum wheel speed difference is less than the slipping determination threshold but the rate of change is greater than the pre-slipping determination threshold, the loader is determined to be in a pre-slipping state; when the maximum wheel speed difference is greater than the slipping determination threshold, the loader is determined to be in a slipping state. The process of limiting the output torque in step S3 specifically includes: calibrating the maximum allowable torque increase rate based on the power output characteristics of the drive motor and the mechanical strength of the transmission system; calculating the torque limit coefficient according to the slippage trend value, wherein the larger the slippage trend value, the smaller the torque limit coefficient; multiplying the maximum allowable torque increase rate by the torque limit coefficient to obtain the torque increase rate limit, and controlling the rate of change of the output torque of the drive motor to not exceed the torque increase rate limit; The process of determining the slippage level and torque adjustment amount in step S4 specifically includes: calibrating a moderate slippage threshold and a severe slippage threshold based on the maximum wheel speed difference and in conjunction with the loader's power characteristics and ground adhesion characteristics, and constructing a slippage level system including mild slippage, moderate slippage, and severe slippage; comparing the maximum wheel speed difference with each slippage threshold level to determine the slippage level and issuing a corresponding warning to the driver; determining a torque reduction coefficient based on the deviation ratio of the maximum wheel speed difference relative to the slippage judgment threshold; multiplying the current output torque by the torque reduction coefficient to obtain the torque adjustment amount, and controlling the output torque of the drive motor to subtract the torque adjustment amount; The process of gradually restoring the output torque in step S4 specifically includes: calculating the deviation between the output torque and the driver's requested value, and dynamically adjusting the torque recovery rate according to the deviation; establishing a positive correlation mapping relationship between the deviation and the torque recovery rate, so that the output torque gradually recovers to the driver's requested value, preventing the torque recovery from being too fast and causing slippage again; if pre-slippage is detected again during the recovery process, the recovery is immediately stopped and the pre-slippage state is re-entered for processing.

2. The method for preventing tire slippage and stabilizing a pure electric loader according to claim 1, characterized in that, The process of continuously monitoring sensor signals and communication status specifically includes: monitoring the effectiveness of each wheel speed sensor signal and the stability of the communication link between the vehicle controller and the drive motor; if an abnormal transmission of a single wheel speed sensor signal is detected, the wheel speed signal of the opposite wheel on the same axle is used as a reference value to calculate and generate a fault signal; if multiple abnormal transmissions of wheel speed sensor signals are detected, the anti-slip control function is stopped and a fault signal is generated; and a warning is issued to the driver based on the fault signal.

3. The method for preventing tire slippage and stabilizing a pure electric loader according to claim 1, characterized in that, The process of determining the slippage trend value specifically includes: normalizing the rate of change to obtain the slippage trend value; establishing a mapping relationship between the slippage trend value and the output torque limiting strength, wherein the slippage trend value represents the current slippage risk level, and the larger the slippage trend value, the greater the corresponding limiting strength of the output torque.

4. A tire slippage prevention and stabilization system for a pure electric loader, characterized in that, The system is used to perform the method according to any one of claims 1 to 3, specifically including: Parameter loading and self-test module: used for configuring and loading control parameters of the vehicle controller, and for self-testing and continuously monitoring the validity of the signals from each wheel speed sensor and the stability of the communication link; Signal acquisition and calculation module: Real-time acquisition of wheel speed signals and current output torque of drive motor, and calculation of maximum wheel speed difference and maximum wheel speed difference change rate in the current cycle; State determination logic module: Receives the calculation results of the signal acquisition and calculation module, and determines whether the loader is currently in a non-slipping state, a pre-slipping state, or a slipping state by comparing the maximum wheel speed difference and its rate of change with a preset threshold. Pre-slip intervention module: Receives the pre-slip state command output by the state determination logic module, normalizes the rate of change to obtain a slip trend value, determines the torque limit coefficient based on the slip trend value, and then calculates the torque increase rate limit. Slip control execution module: Receives slip status command output by the status determination logic module, determines the current slip level and determines the torque reduction coefficient according to the deviation ratio of the maximum wheel speed difference relative to the slip determination threshold, and eliminates slip by controlling the output torque to subtract the torque adjustment amount determined by the torque reduction coefficient; Dynamic recovery control module: After slippage is eliminated, it calculates the torque recovery rate in real time based on the deviation between the current output torque and the driver's requested value, so that the output torque gradually recovers to the driver's requested value, and monitors the risk of slippage again during the recovery process; Alarm prompt module: Receives the slippage level information output by the state determination logic module or the fault signal output by the parameter loading and self-test module, and issues a corresponding level of visual or auditory alarm prompt to the driver.

Images