Heavy-load differential rudder wheel adaptive hydraulic load closed-loop control method and related equipment

Abstract

The application relates to a heavy-load differential steering wheel adaptive hydraulic load closed-loop control method and related equipment, and relates to the field of industrial control. The method comprises the following steps: calculating a deformation variable change amount according to a tire deformation variable feedback signal, establishing a load prediction model in combination with a preset tire stiffness coefficient, and obtaining a predicted load fluctuation amount; taking a preset target load as a control target, taking a hydraulic load feedback signal as a main feedback, taking the predicted load fluctuation amount as a feedforward compensation amount, performing double-feedback closed-loop adjustment, and outputting a control voltage to adjust the valve opening degree of a hydraulic execution unit; calculating the current difference value and current balance degree of the current signals of left and right drive motors; based on a pre-established coupling mathematical model, the theoretical load value under the current working condition is calculated, the theoretical load value is compared with the hydraulic load feedback signal, and if the deviation exceeds a set threshold, it is determined that the differential steering wheel is abnormal and an alarm is triggered. The above technical scheme can accurately control the hydraulic load.

Description

Technical Field

[0001] This application relates to the field of industrial control, and in particular to a method and related equipment for adaptive hydraulic load closed-loop control of heavy-duty differential steering wheels. Background Technology

[0002] Heavy-duty Automated Guided Vehicles (AGVs) are core material handling equipment in fields such as intelligent manufacturing, port logistics, and heavy equipment transfer. Their load-bearing capacity and operational reliability directly impact production efficiency and operational safety. The heavy-duty differential steering wheel is the core actuation component of the heavy-duty AGV. It employs a structure with independent left and right motor drives and an internal differential mechanism. By controlling the speed difference between the left and right drive motors, the vehicle can move forward, backward, turn, and rotate in place. Because heavy-duty AGVs are subjected to large vertical static loads, dynamic impact loads, and differential shear forces over extended periods, the heavy-duty differential steering wheel places extremely high demands on structural strength, tire deformation characteristics, balanced output of the two motors, and durability reliability. Therefore, performance verification and durability testing must be conducted on a professional loading test platform.

[0003] Existing testing systems often employ single-pressure closed-loop control for hydraulic load control, relying solely on pressure sensor feedback for constant pressure regulation. This control method fails to consider the deformation characteristics of the tires on heavy-duty differential steering wheels under pressure, making it impossible to predict and compensate for load fluctuations in advance. It also cannot accurately simulate the actual load environment of heavy-duty differential steering wheels during operation, directly impacting the accuracy and reliability of test results. Existing systems can only record independent test data from each sensor, lacking the ability to perform coupled analysis of synchronously acquired multiple parameters. Furthermore, existing systems lack effective online identification methods for early faults such as uneven output from dual motors, differential mechanism jamming, and uneven tire wear, making it difficult to detect potential abnormalities in the steering wheels in a timely manner. Summary of the Invention

[0004] This application provides a closed-loop control method and related equipment for adaptive hydraulic load of heavy-duty differential steering wheel, which can accurately control hydraulic load, effectively predict load fluctuations, and promptly detect abnormal conditions of differential steering wheel.

[0005] Firstly, this application provides a method for adaptive hydraulic load closed-loop control of a heavy-duty differential steering wheel, the method comprising: Through the synchronous triggering logic of the multi-sensor acquisition unit, the hydraulic load feedback signal of the pressure sensor, the tire deformation feedback signal of the laser displacement sensor, and the current signal of the left drive motor and the right drive motor of the differential steering wheel under test are synchronously acquired at the current moment. The main control unit calculates the deformation change based on the tire deformation feedback signal and establishes a load prediction model in conjunction with the preset tire stiffness coefficient to obtain the predicted load fluctuation for feedforward compensation. The main control unit uses a preset target load as the control target, the hydraulic load feedback signal as the main feedback, and the predicted load fluctuation as the feedforward compensation amount. It performs dual feedback closed-loop regulation through a PID algorithm and outputs control voltage to adjust the valve opening of the hydraulic actuator until the difference between the measured load and the target load is less than the preset difference and enters the steady-state holding stage. During the steady-state holding phase, the main control unit calculates the current difference and current balance between the current signals of the left drive motor and the right drive motor. The main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model consisting of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, it is determined that there is an abnormality in the differential steering wheel and an alarm is triggered.

[0006] By adopting the above technical solution, under dynamic lifting and load change conditions, it is possible to predict and compensate before the actual load changes, effectively suppressing load overshoot and fluctuations, and ensuring that the measured load converges quickly and stably to the target load, thus solving the problem of insufficient load stability under dynamic conditions. Furthermore, by integrating independent parameters into a unified comprehensive performance evaluation criterion, it solves the problems of multi-parameter timing misalignment, inability to identify faults early, and low data utilization in existing technologies.

[0007] In some embodiments, the step of using the main control unit to control a preset target load as the control target, using the hydraulic load feedback signal as the main feedback and the predicted load fluctuation as the feedforward compensation amount, and performing dual feedback closed-loop regulation through a PID algorithm to output a control voltage to adjust the valve opening of the hydraulic actuator specifically includes: The main control unit performs zero-point calibration and standardization on the hydraulic load feedback signal to eliminate sensor system errors and obtain the calibrated real-time load value. The main control unit calculates the difference between the target load and the calibrated real-time load value as the load control deviation at the current moment. The main control unit inputs the load control deviation into the PID controller for proportional, integral, and derivative operations to obtain the first control component, and multiplies the predicted load fluctuation by a preset feedforward coefficient to obtain the second control component. The main control unit superimposes the first control component and the second control component to generate the final control voltage, which is then output to the hydraulic valve group of the hydraulic actuator to dynamically adjust the valve opening.

[0008] By adopting the above technical solution, the control voltage is decomposed into a PID feedback regulation component based on pressure error and a feedforward compensation component based on deformation prediction. The combined output is used to achieve composite regulation of valve opening. The two work together to enable the system to respond quickly and suppress load overshoot under dynamic conditions such as lifting and lowering start-up and sudden load changes. This solves the problem of slow response and large fluctuations in the response of existing single pressure closed-loop control in dynamic processes.

[0009] In some embodiments, the step of using the main control unit to control a preset target load as the control target, using the hydraulic load feedback signal as the main feedback and the predicted load fluctuation as the feedforward compensation amount, and performing dual feedback closed-loop regulation through a PID algorithm to output a control voltage to adjust the valve opening of the hydraulic actuator specifically includes: The calibrated real-time load value is calculated using the following formula: ; in, F cal This indicates the real-time load value after calibration. K p This indicates the calibration coefficient of the pressure sensor. I p This indicates the real-time output current value of the pressure sensor. I p0 This indicates the zero-point current value of the pressure sensor. F 0 Indicates the zero-point load offset; The load control deviation is calculated using the following formula: e ( t )= F set - F cal ; in, e ( t This indicates the load control deviation at the current moment. F set Indicates the target load; The first control component is calculated using the following formula: ; in, U fb ( t ) represents the first control component. , , These are the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively. The second control component is calculated using the following formula: Uff ( t )= K ff ×△ F pre ; in, U ff ( t ) represents the second control component. K ff This represents the preset feedforward coefficient, Δ F pre This indicates the predicted load fluctuation amount; The final control voltage is calculated using the following formula: U ( t )= U fb ( t )+ U ff ( t ); in, U ( t ) represents the final control voltage.

[0010] In some embodiments, the main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model composed of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is then compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, an abnormality is determined in the differential steering wheel, and an alarm is triggered. Specifically, this includes: The main control unit performs zero-point calibration and calibration on the current signals of the left drive motor and the right drive motor respectively to obtain the calibrated current values ​​of the left motor and the right motor. The main control unit calculates the current difference and current balance based on the calibrated left motor current value and the calibrated right motor current value, and compares them with the preset current difference threshold and balance threshold respectively. If the current difference exceeds the current difference threshold or the current balance is lower than the balance threshold, it is determined that the output of the two motors is uneven and an alarm is triggered. The main control unit inputs the tire deformation feedback signal, the calibrated left motor current value, and the calibrated right motor current value at the current moment into the coupled mathematical model to calculate the theoretical load value under the current working condition. The main control unit calculates the percentage deviation between the theoretical load value and the calibrated real-time load value. If the percentage deviation exceeds a preset deviation threshold, it determines that the steering wheel has uneven tire wear or differential mechanism jamming and triggers an alarm.

[0011] By adopting the above technical solution, zero-point calibration and standardization calibration are performed on the current signals of the left and right drive motors respectively to eliminate the zero drift and gain error of the Hall current sensor. Based on this, the current difference and current balance are calculated and quantitatively compared with the preset threshold. This achieves an objective and quantitative judgment of uneven output of the two motors, and can identify whether the output of the two motors is balanced online, providing a direct basis for the health status assessment of the differential mechanism.

[0012] In some embodiments, the main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model composed of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is then compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, an abnormality is determined in the differential steering wheel, and an alarm is triggered. Specifically, this includes: Zero-point calibration and standardization calibration are performed on the current signals of the left drive motor and the right drive motor respectively using the following formulas: ; ; in, I L，cal This indicates the current value of the left motor after calibration. I R，cal This indicates the current value of the right motor after calibration. K i This represents the calibration coefficient of the current sensor. U L , U R These represent the real-time output voltage values ​​of the left and right motor current acquisition channels, respectively. U i0 This is the zero-point voltage value of the current sensor; The current difference is calculated using the following formula: ; Among them, △ I This represents the current difference; The current balance is calculated using the following formula: ; in, This indicates the degree of current balance. min This represents the minimum value. maxIndicates the maximum value; The theoretical load value is calculated using the following formula: ; in, F pred represents the theoretical load value, s represents the deformation value corresponding to the tire deformation feedback signal, and a, b, and c represent the coupling coefficients, respectively. The percentage deviation is calculated using the following formula: ; in, This indicates the percentage of deviation. F cal This indicates the real-time load value after calibration.

[0013] In some embodiments, the hydraulic load closed-loop control system further includes a power supply isolation unit and a data storage and interaction unit, and the method further includes: The power supply isolation unit provides electrical isolation power to the hydraulic load closed-loop control system. AC power is used to provide power to the hydraulic actuator and the main control unit, an independent battery is used to provide drive power to the differential steering wheel under test, and electrical isolation between the power circuit and the signal acquisition circuit is achieved through an isolation transformer and an optocoupler. During the steady-state holding phase, the test data of each acquisition channel is recorded and stored in real time through the data storage and interaction unit. The test data includes the current number of cycles, the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, the current signal of the right drive motor, and the control voltage signal output by the main control unit. The main control unit controls the hydraulic actuator to sequentially execute the loading phase, pressure holding phase, and unloading phase according to the preset automatic cycle durability control logic. After completing a single cycle, the cycle count is updated until the current cycle count equals the target cycle count, at which point the test stops. All test data is then stored in the local storage medium through the data storage and interaction unit.

[0014] By adopting the above technical solution, a dual-power supply architecture is used, which uses AC power to power the hydraulic actuator and main control unit and an independent battery to power the differential steering wheel under test. With the help of isolation transformers and optocouplers, complete electrical isolation between the power circuit and the signal acquisition circuit is achieved. This effectively blocks the electromagnetic interference generated by the start-up and shutdown of high-power equipment in the hydraulic station and the switching of frequency converters from being conducted along the power supply line to the signal acquisition circuit. This solves the problems of data distortion and control signal fluctuation caused by the shared power supply system in the prior art, and provides a clean electrical environment for the stable operation of high-precision synchronous acquisition and closed-loop control algorithms.

[0015] In some embodiments, the step of controlling the hydraulic actuator to sequentially execute the loading phase, pressure holding phase, and unloading phase according to a preset automatic cycle durability control logic by the main control unit, and updating the cycle count after completing a single cycle, specifically includes: During the loading phase, the main control unit controls the valve opening of the hydraulic actuator to gradually increase from the initial state at a preset loading speed, so that the measured load rises linearly from zero to the target load, and the actual time consumed during the loading phase is recorded. During the pressure holding phase, the main control unit continuously executes the dual feedback closed-loop adjustment to keep the measured load within the preset error range of the target load and maintain the preset pressure holding duration. During the pressure holding duration, the test data of each acquisition channel are continuously recorded. During the unloading phase, the main control unit controls the valve opening of the hydraulic actuator to gradually decrease at a preset unloading speed, so that the measured load drops from the target load to zero, and the actual time consumed during the unloading phase is recorded. After completing a single loop, the main control unit increments the loop count and determines whether the current loop count has reached the preset target loop count. If it has not reached the target, it automatically enters the loading phase of the next loop; if it has reached the target, it stops the test and triggers a data storage command.

[0016] By adopting the above technical solution, a time-sharing switching strategy of "speed control in the lifting stage + precision control in the pressure holding stage" is used to balance the stability of the dynamic process and the accuracy of the steady-state process, thus solving the problems of the single three-stage control strategy, large load impact in the dynamic process, and large fluctuations in the pressure holding stage in the existing technology.

[0017] In a second aspect, embodiments of this application provide a computer system including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program to implement the steps of the method described in any possible implementation of the first aspect.

[0018] Thirdly, embodiments of this application provide a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implement the steps of the method described in any possible implementation of the first aspect.

[0019] Fourthly, embodiments of this application provide a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the method described in any possible implementation of the first aspect.

[0020] It is understood that the computer system provided in the second aspect, the storage medium provided in the third aspect, and the computer program product provided in the fourth aspect are all used to execute the method provided in this application. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here.

[0021] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. By using the synchronous triggering logic of the multi-sensor acquisition unit, the hydraulic load signal of the pressure sensor, the tire deformation signal of the laser displacement sensor, and the dual-channel current signal of the left and right drive motors are acquired simultaneously at the same time. The time consistency of the four signals is guaranteed from the hardware level, which provides a precise data foundation for subsequent dual-motor coupling characteristic analysis and load-deformation-current correlation modeling. This solves the problem that the timing misalignment of multiple parameters makes it impossible to accurately analyze the cooperative characteristics of dual motors. 2. The dual-feedback closed-loop control architecture, which uses the hydraulic load feedback signal as the main feedback and the tire deformation prediction load fluctuation as the feedforward compensation, enables the system to predict and adjust the valve opening in advance before the actual load deviates from the target value under dynamic lifting and sudden load changes. This effectively suppresses load overshoot and fluctuation, and allows the measured load to quickly converge to the target value and enter the steady-state holding stage. This solves the problems of slow response and large load fluctuation in the existing single pressure closed-loop control under dynamic conditions. 3. During the steady-state maintenance phase, the system simultaneously performs state monitoring in two dimensions: dual-motor balance judgment and multi-parameter coupled model comparison. On the one hand, it assesses the balance of output of the dual motors online by using current difference and current balance. On the other hand, it substitutes the real-time collected deformation and dual current into the coupled mathematical model to calculate the theoretical load. By comparing it with the actual hydraulic load, it identifies mechanical anomalies such as uneven tire wear and differential mechanism jamming. It integrates the originally independent pressure, deformation, and current parameters into a unified comprehensive performance judgment basis, solving the problems of independent recording of multiple parameters, lack of fusion analysis capability, and inability to identify early faults in the existing technology. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the adaptive hydraulic load closed-loop control method for heavy-duty differential steering wheels in an embodiment of this application. Figure 2 This is a schematic diagram of the process of generating and outputting control voltage in an embodiment of this application; Figure 3 This is a schematic diagram of an exemplary hardware structure of a computer system in an embodiment of this application. Detailed Implementation

[0023] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to any or all possible combinations including one or more of the listed items.

[0024] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0025] The following is combined Figure 1 The method of the embodiments of this application will be described below.

[0026] Please see Figure 1 This is a flowchart illustrating the adaptive hydraulic load closed-loop control method for heavy-duty differential steering wheels in this embodiment of the application. The method is applied to a hydraulic load closed-loop control system, which includes a main control unit, a multi-sensor acquisition unit, and a hydraulic execution unit, such as... Figure 1 As shown, the method includes the following steps: S101. Through the synchronous triggering logic of the multi-sensor acquisition unit, the hydraulic load feedback signal of the pressure sensor, the tire deformation feedback signal of the laser displacement sensor, and the current signal of the left drive motor and the right drive motor of the differential steering wheel under test are synchronously acquired at the current moment. S102. The main control unit calculates the change in deformation based on the tire deformation feedback signal, and establishes a load prediction model in combination with the preset tire stiffness coefficient to obtain the predicted load fluctuation for feedforward compensation. S103. The main control unit uses the preset target load as the control target, the hydraulic load feedback signal as the main feedback, and the predicted load fluctuation as the feedforward compensation amount. It performs dual feedback closed-loop regulation through PID algorithm and outputs control voltage to adjust the valve opening of the hydraulic actuator until the difference between the measured load and the target load is less than the preset difference and enters the steady-state holding stage. S104. During the steady-state holding phase, the main control unit calculates the current difference and current balance between the current signals of the left drive motor and the right drive motor. S105. The main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model consisting of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, it is determined that there is an abnormality in the differential steering wheel and an alarm is triggered.

[0027] The synchronous triggering logic of the multi-sensor acquisition unit incorporates a synchronous sampling trigger circuit at the hardware level. When the system starts acquisition, the main control unit sends a synchronous sampling trigger pulse to the multi-sensor acquisition unit. This pulse simultaneously drives four acquisition channels: the pressure sensor acquisition channel, the laser displacement sensor acquisition channel, the left motor current acquisition channel, and the right motor current acquisition channel, initiating sampling concurrently. Specifically, the pressure sensor uses a strain gauge type, installed at the output end of the hydraulic cylinder, to acquire the hydraulic load signal in real time and output a 4-20mA standard analog signal. The laser displacement sensor is installed above the pressure plate, acquiring the distance between the pressure plate and the differential steering wheel surface in real time and converting it into a tire deformation signal. The current signals of the left and right drive motors are acquired through Hall current sensors, which collect the real-time operating current of the two motors respectively. All four channels complete sampling synchronously under the drive of the same trigger pulse, ensuring the consistency of the four signals on the time axis, with the sampling timing error controlled within 1ms. By replacing software post-alignment with hardware synchronous triggering, the problem of multi-parameter timing misalignment is solved at its source.

[0028] The main control unit uses real-time tire deformation feedback signals collected by a laser displacement sensor to calculate the deformation change, i.e., the magnitude and direction of the tire deformation change relative to the previous moment. Based on this, the main control unit establishes a load prediction model using a preset tire stiffness coefficient. The tire stiffness coefficient, a physical parameter obtained through prior calibration, reflects the load change per unit deformation of the heavy-duty differential steering wheel tire of this model. By substituting the real-time calculated deformation change into the load prediction model, the load fluctuation expected under the current deformation trend can be calculated, i.e., the predicted load fluctuation. For example, when the tire deformation continuously increases during the steering wheel loading process, the prediction model will calculate the upcoming increase in load value; when the deformation tends to stabilize, the prediction model indicates that the load will remain stable. Because tire deformation occurs before significant load changes (deformation is the result of load action, but the trend of deformation indicates the direction of load change), this allows the system to obtain early warning information before the load actually deviates from the target value, providing a time lead for feedforward compensation in subsequent steps.

[0029] Existing hydraulic load control systems mostly employ single-pressure closed-loop control, relying solely on pressure sensor feedback for constant pressure regulation. This single-feedback control method is reactive, meaning it only responds after the load has deviated from the target value, leading to lag, load overshoot, and significant fluctuations under dynamic conditions. To address these shortcomings, this application introduces a dual-feedback closed-loop control architecture of "main feedback + feedforward compensation," whose working principle can be divided into three levels: First, the establishment of the main feedback channel. The main control unit uses a preset target load as the control objective and uses the real-time acquired hydraulic load feedback signal as the main feedback quantity. The main feedback channel operates using a PID (proportional-integral-derivative) algorithm: the proportional element adjusts instantly based on the current error, the integral element eliminates steady-state residual error, and the derivative element predicts the error change trend. The main feedback channel ensures that the system can accurately maintain the target load under steady-state conditions. Second, the introduction of the feedforward compensation channel. The main control unit uses the obtained predicted load fluctuation as the feedforward compensation quantity. The working principle of feedforward compensation is: before the actual load change, the valve opening is adjusted in advance based on the predicted tire deformation information. Specifically, when the predicted load fluctuation indicates an impending load increase, the system reduces the valve opening in advance to suppress overshoot; when the predicted load fluctuation indicates an impending load decrease, the system increases the valve opening in advance to compensate for the shortfall. The characteristic of feedforward compensation is proactive adjustment, meaning it takes action before the actual deviation occurs. Third, the dual-channel coordinated output. The main control unit superimposes the feedback adjustment component calculated by the PID algorithm with the feedforward compensation component to generate the final control voltage (0-10V range), which is output to the hydraulic valve group of the hydraulic actuator to dynamically adjust the valve opening, thereby controlling the lifting speed and output load of the hydraulic cylinder. The feedback channel is responsible for correction, and the feedforward channel is responsible for prediction; the two work together to enable the system to respond quickly and effectively suppress load overshoot under dynamic conditions such as lifting and lowering starts and sudden load changes. The main control unit continuously executes the above dual-feedback closed-loop adjustment until the difference between the measured load and the target load is less than a preset difference. At this point, the system determines that the load has stabilized and enters the steady-state holding phase. During the steady-state holding phase, the integral action of the main feedback channel continuously eliminates small residual errors, ensuring the load is precisely maintained near the target value.

[0030] The heavy-duty differential steering wheel adopts a structure with independent left and right dual motors and an internal differential mechanism. Forward, reverse, steering, and stationary rotation are achieved by controlling the speed difference between the left and right drive motors. The output balance of the dual motors is a key indicator for assessing the health of the differential steering wheel. Uneven output between the left and right motors not only reduces transmission efficiency and accelerates tire wear but may also indicate abnormalities in the differential mechanism. However, existing testing systems can only record the current values ​​of the two motors separately, lacking a means to automatically determine the cooperative state of the two motors. To address these shortcomings, this application's embodiment, during the steady-state holding phase where the load has stabilized, utilizes the synchronously acquired left and right drive motor current signals for two key calculations performed by the main control unit: First, current difference calculation. The main control unit calculates the absolute difference between the current of the left and right drive motors. The current difference directly reflects the degree of difference in the instantaneous output of the two motors; the larger the difference, the more unbalanced the output of the two motors. Under normal operating conditions, the current of the left and right motors of the differential steering wheel should remain similar. If the difference is significantly larger, it may indicate an abnormality in one of the motors or a malfunction in the differential mechanism. Secondly, current balance is calculated. The main control unit further calculates the current balance, which is the ratio (expressed as a percentage) of the smaller to the larger current value of the left and right motors. Balance assesses the coordination of the two motors from a relative proportion perspective. The closer the balance is to 100%, the more balanced the output of the two motors; the lower the balance, the greater the difference in output between the two motors. Through these two quantitative indicators—current difference and current balance—the system transforms the originally ambiguous question of whether the two motors are coordinating into a quantifiable and comparable numerical judgment.

[0031] This application introduces a deep anomaly identification mechanism based on a coupled mathematical model. Its working principle can be divided into three levels: First, the pre-construction of the coupled mathematical model. This model is established during the initial calibration phase and reflects the inherent correlation between four physical quantities—hydraulic load, tire deformation, left motor current, and right motor current—when a heavy-duty differential steering wheel is operating normally under healthy conditions. Specifically, the model takes tire deformation, left motor current, and right motor current as inputs and outputs the theoretically expected hydraulic load value under this condition. Essentially, this model is a mathematical expression of the steering wheel's healthy state; under the condition that all components of the steering wheel are operating normally, the four parameters should satisfy the mapping relationship described by this model. Second, real-time calculation and comparison of theoretical load values. During the steady-state holding phase, the main control unit substitutes the currently synchronously acquired tire deformation feedback signal, left drive motor current signal, and right drive motor current signal into the pre-constructed coupled mathematical model to calculate the theoretical load value under the current condition. Subsequently, the main control unit compares this theoretical load value with the actually acquired hydraulic load feedback signal. The deviation between the two reflects the degree of discrepancy between the actual physical characteristics of the steering wheel and the health status model. Third, anomaly detection and alarm triggering. The main control unit calculates the percentage deviation between the theoretical load value and the actual load value and compares it with a preset deviation threshold. If the deviation exceeds the set threshold, an anomaly is detected in the steering wheel, and an alarm is triggered. Different anomaly modes lead to different deviation characteristics: uneven tire wear changes the mapping relationship between tire deformation and load, causing a deviation between the theoretical load calculated based on deformation and the actual load; differential mechanism jamming changes the conversion efficiency between current and output load, also leading to a deviation between the theoretical and actual values.

[0032] Figure 2 This is a schematic diagram of the process for generating and outputting control voltage in an embodiment of this application, as shown below. Figure 2 As shown, the process involves using the main control unit with a preset target load as the control target, the hydraulic load feedback signal as the main feedback, and the predicted load fluctuation as the feedforward compensation, to perform dual-feedback closed-loop regulation through a PID algorithm, and outputting a control voltage to adjust the valve opening of the hydraulic actuator. Specifically, this includes: S201. The main control unit performs zero-point calibration and calibration on the hydraulic load feedback signal to eliminate sensor system errors and obtain the calibrated real-time load value. S202. The difference between the target load and the calibrated real-time load value is calculated by the main control unit as the load control deviation at the current moment. S203. The load control deviation is input into the PID controller through the main control unit to perform proportional, integral and derivative operations to obtain the first control component, and the predicted load fluctuation is multiplied by the preset feedforward coefficient to obtain the second control component. S204. The first control component and the second control component are superimposed by the main control unit to generate the final control voltage and output it to the hydraulic valve group of the hydraulic actuator to dynamically adjust the valve opening.

[0033] When a sensor is under no-load conditions, it may produce a non-zero output (i.e., zero-point drift) due to factors such as temperature changes, fatigue of elastic elements caused by long-term use, and fluctuations in power supply voltage. At full scale, gain errors may cause the output value to be disproportionate to the actual pressure (i.e., sensitivity drift). If these systematic errors are not eliminated, they will directly cause the hydraulic load feedback signal acquired by the main control unit to deviate from the true value, thus affecting the accuracy of subsequent closed-loop control. In this embodiment, before executing closed-loop control, the main control unit performs two-stage calibration processing on the raw hydraulic load feedback signal acquired by the pressure sensor: Stage 1 – Zero-point calibration. When the hydraulic cylinder is in a completely unloaded state (i.e., no external load), the main control unit reads the output value of the pressure sensor. Ideally, the output should be zero (corresponding to a 4mA standard signal), but due to the aforementioned drift factors, the actual output often has a fixed offset. The main control unit records this offset as the zero-point deviation value and subtracts this deviation from all subsequent acquired data to ensure that the feedback value is zero under no-load conditions. Stage 2 – Calibration calibration. Based on the zero-point calibration, the main control unit performs gain calibration on the sensor using a known standard load. In practice, a reference pressure can be generated by applying a standard weight of known weight or using a calibrated standard pressure source. The sensor's output value under this reference pressure is compared with the theoretical value to calculate the sensor's calibration coefficient. This calibration coefficient reflects the proportional relationship between the sensor's output signal and the actual load. Through the above two-stage calibration process, the main control unit substitutes the original acquired signal into the calibration formula to obtain the calibrated real-time load value after eliminating zero-point offset and gain error. This value accurately reflects the actual load currently output by the hydraulic cylinder, providing accurate and reliable feedback input for subsequent closed-loop control.

[0034] After obtaining the calibrated real-time load value, the main control unit needs to determine the difference between the current measured load and the expected load, using this as the basis for control decisions. The main control unit stores a pre-set target load value, set by the tester through a human-machine interface (such as a touchscreen) according to specific test conditions. This value represents the rated load the system expects the hydraulic cylinder to output. The main control unit subtracts the target load from the calibrated real-time load value, calculating the difference. The physical meaning of this difference is "the degree and direction of the current load deviating from the target value": if the difference is positive, it means the measured load is lower than the target load, and the system needs to increase the valve opening to increase the output load; if the difference is negative, it means the measured load is higher than the target load, and the system needs to decrease the valve opening to reduce the output load; if the difference is zero or within the allowable range, it means the measured load is close to the target value, and the system can maintain its current state.

[0035] After obtaining the load control deviation, the main control unit performs two simultaneous calculations, generating a first control component (feedback adjustment component) and a second control component (feedforward compensation component), which are then superimposed and output in subsequent steps. The main control unit inputs the load control deviation into the PID controller. The PID controller is the most classic control algorithm in industrial process control, containing three parallel calculation channels: Proportional (P): Multiplies the current deviation by a proportional coefficient. The proportional element adjusts in real time according to the magnitude of the current error; the larger the error, the larger the adjustment range; the smaller the error, the smaller the adjustment range. Proportional control is characterized by rapid response, but it is difficult to completely eliminate residual error when used alone. Integral (I): Multiplies the cumulative value of the deviation over time by an integral coefficient. The integral element accumulates historical errors; as long as residual error exists in the system, the integral term will continue to increase until the error is completely eliminated. Integral control is characterized by its ability to eliminate steady-state error, but its response speed is relatively slow. Differential (D): Multiplies the rate of change of the deviation (i.e., the rate of change of the deviation at the current moment relative to the deviation at the previous moment) by a differential coefficient. The derivative term makes predictive adjustments based on the trend of error changes. When the error is rapidly increasing, the derivative term outputs a larger adjustment amount in advance to suppress overshoot; when the error is rapidly decreasing, the derivative term reduces the adjustment amount in advance to prevent oscillation. The characteristic of derivative control is its forward-looking nature, which improves the dynamic response characteristics of the system. The PID controller superimposes the outputs of the three calculation channels to generate the first control component, whose core function is "correction," that is, pulling the measured load back to the target value. Parallel to the first control component, the main control unit simultaneously multiplies the predicted load fluctuation by a preset feedforward coefficient to obtain the second control component. The feedforward coefficient is a weighting factor determined in advance through debugging, used to adjust the strength of feedforward compensation. If the coefficient is too small, the compensation is insufficient; if the coefficient is too large, it may cause overcompensation. The essential difference between feedforward control and feedback control is that feedback control performs "post-event correction" after the deviation has occurred, while feedforward control performs "pre-event prevention" based on predictive information before the deviation occurs. In this embodiment, the predicted load fluctuation amount is derived from the precursor information of tire deformation. This information already indicates the impending load change trend before the actual load deviates from the target value. The predicted load fluctuation amount is multiplied by an appropriate feedforward coefficient and used as the second control component, enabling the system to output the corresponding adjustment amount in advance before the actual load change, thereby effectively suppressing load overshoot and fluctuation during the dynamic process.

[0036] The main control unit algebraically superimposes the calculated first control component (feedback adjustment) and second control component (feedforward compensation) to generate the final control voltage signal. This control voltage ranges from 0-10V, a standard industrial analog signal. This control voltage is output to the hydraulic valve assembly of the hydraulic actuator. The proportional or servo valves in the hydraulic valve assembly exhibit voltage-opening correspondence characteristics; the magnitude of the input voltage determines the displacement of the valve core, which in turn determines the effective flow area of ​​the valve orifice. Specifically: when the control voltage increases, the valve opening increases, the hydraulic oil flow increases, and the hydraulic cylinder output load increases; when the control voltage decreases, the valve opening decreases, the hydraulic oil flow decreases, and the hydraulic cylinder output load decreases. The two control components work in tandem: the first control component (feedback adjustment) and the second control component (feedforward compensation) complement each other in the time dimension. Feedforward compensation acts in advance before the actual load deviation occurs, playing a "preemptive adjustment" role and effectively suppressing load fluctuations during the dynamic process; feedback adjustment continuously monitors and corrects residual errors to ensure steady-state accuracy. The two work together to enable the system to accurately maintain the target load under static conditions and to respond quickly and effectively suppress overshoot and fluctuations during dynamic lifting and lowering processes. This fundamentally solves the problems of slow response and large load fluctuations in existing single pressure closed-loop control under dynamic conditions.

[0037] In some embodiments, the step of using the main control unit to control a preset target load as the control target, using the hydraulic load feedback signal as the main feedback and the predicted load fluctuation as the feedforward compensation amount, and performing dual feedback closed-loop regulation through a PID algorithm to output a control voltage to adjust the valve opening of the hydraulic actuator specifically includes: The calibrated real-time load value is calculated using the following formula: ; in, F cal This indicates the real-time load value after calibration. K p This indicates the calibration coefficient of the pressure sensor. I p This indicates the real-time output current value of the pressure sensor. I p0 This indicates the zero-point current value of the pressure sensor. F 0 Indicates the zero-point load offset; The load control deviation is calculated using the following formula: e ( t )= F set - F cal ; in, e (t This indicates the load control deviation at the current moment. F set Indicates the target load; The first control component is calculated using the following formula: ; in, U fb ( t ) represents the first control component. , , These are the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively. The second control component is calculated using the following formula: U ff ( t )= K ff ×△ F pre ; in, U ff ( t ) represents the second control component. K ff This represents the preset feedforward coefficient, Δ F pre This indicates the predicted load fluctuation amount; The final control voltage is calculated using the following formula: U ( t )= U fb ( t )+ U ff ( t ); in, U ( t ) represents the final control voltage.

[0038] Calculate the real-time load value after calibration: Subtract the zero-point current from the real-time output current of the sensor to obtain the effective current increment after deducting zero-point drift; then multiply this current increment by the calibration coefficient to convert the current change into a load change; finally, add the zero-point load offset to complete the entire calibration. The result obtained through the above calculation is the real-time load value after calibration, eliminating zero-point drift and sensitivity error. The engineering significance of this formula is that strain gauge pressure sensors commonly suffer from two types of systematic errors in practical use: zero-point drift (caused by changes in ambient temperature, creep of elastic elements after long-term stress, etc.) and sensitivity drift (changes in sensor gain over time). If calibration is not performed and the original acquired signal is used directly as control feedback, it will lead to a deviation between the feedback value and the actual load, thus affecting the accuracy of subsequent closed-loop control. Through this formula, the main control unit can quickly complete the calibration processing of the sensor signal in each control cycle, providing accurate and reliable feedback input for closed-loop control.

[0039] Calculate the load control deviation: when e ( t When the measured load is greater than 0, the actual load is lower than the target load, and the system needs to increase the valve opening to increase the output load; when e ( t When the measured load is less than 0, the actual load is higher than the target load, and the system needs to reduce the valve opening to lower the output load; when e ( t When the deviation approaches zero, the measured load is close to the target value, and the system can maintain its current state. This deviation is a quantitative assessment of the current control effect of the system. The magnitude and direction of the deviation directly determine the adjustment range and direction that the PID controller needs to output, making it the most critical intermediate variable in the entire closed-loop control chain.

[0040] The first control component is calculated as follows: The proportional term multiplies the current deviation by a proportional coefficient. The proportional element adjusts in real time according to the magnitude of the current error; the larger the error, the larger the adjustment range; the smaller the error, the smaller the adjustment range. Proportional control is characterized by rapid response, able to react quickly to sudden deviations. However, when used alone, because proportional adjustment requires the existence of an error to produce a control effect, it is difficult to completely eliminate residual error (i.e., steady-state error). A trade-off is needed when choosing the value of the proportional coefficient: a larger value results in a fast response but may cause system oscillation; a smaller value results in system stability but a slow response. The integral term multiplies the integral value of the deviation from the control system's start-up time 0 to the current time t (i.e., the cumulative sum of historical errors) by an integral coefficient. The integral element continuously accumulates historical errors; as long as residual errors exist in the system, the integral term will continuously accumulate and increase over time until a sufficiently large control output completely eliminates the error. Integral control is characterized by its ability to eliminate steady-state errors, allowing the measured load to accurately converge to the target value in the steady-state phase. However, its response speed is relatively slow, and excessive integral action may cause system overshoot. The value of the integral coefficient determines the strength of the integral action. The derivative term multiplies the rate of change of the deviation (i.e., the rate of change of the deviation at the current time relative to the deviation at the previous time) by the derivative coefficient. The derivative term makes predictive adjustments based on the trend and rate of error change. When the error is rapidly increasing, the derivative term outputs a larger adjustment amount in advance to suppress impending overshoot; when the error is rapidly decreasing, the derivative term decreases the adjustment amount in advance to prevent over-adjustment. The characteristic of derivative control is its foresight, which can improve the dynamic response characteristics of the system and suppress overshoot and oscillation. However, the derivative action is sensitive to noise, and its value needs to be set carefully. The PID controller superimposes the outputs of the above three calculation channels to obtain the first control component.

[0041] Calculate the second control component: Multiply the predicted load fluctuation by the feedforward coefficient to obtain the feedforward compensation control component proportional to the predicted fluctuation. Unlike the first control component, the second control component is not calculated based on "already occurred deviations," but rather based on "the future load fluctuation trend predicted by the precursor signal of tire deformation." Before the load actually deviates from the target value, the system has already obtained information about the impending fluctuation and outputs the compensation control quantity accordingly.

[0042] The main control unit algebraically superimposes the feedback adjustment amount (first control component) based on deviation calculation and the feedforward compensation amount (second control component) based on deformation prediction, and outputs a control voltage within the standard industrial analog signal range of 0-10V. The magnitude of this control voltage determines the displacement of the valve core in the hydraulic valve group. When the voltage increases, the valve opening increases, the hydraulic flow increases, and the output load increases; when the voltage decreases, the valve opening decreases, the hydraulic flow decreases, and the output load decreases.

[0043] In some embodiments, the main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model composed of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is then compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, an abnormality is determined in the differential steering wheel, and an alarm is triggered. Specifically, this includes: The main control unit performs zero-point calibration and calibration on the current signals of the left drive motor and the right drive motor respectively to obtain the calibrated current values ​​of the left motor and the right motor. The main control unit calculates the current difference and current balance based on the calibrated left motor current value and the calibrated right motor current value, and compares them with the preset current difference threshold and balance threshold respectively. If the current difference exceeds the current difference threshold or the current balance is lower than the balance threshold, it is determined that the output of the two motors is uneven and an alarm is triggered. The main control unit inputs the tire deformation feedback signal, the calibrated left motor current value, and the calibrated right motor current value at the current moment into the coupled mathematical model to calculate the theoretical load value under the current working condition. The main control unit calculates the percentage deviation between the theoretical load value and the calibrated real-time load value. If the percentage deviation exceeds a preset deviation threshold, it determines that the steering wheel has uneven tire wear or differential mechanism jamming and triggers an alarm.

[0044] Before performing comparative analysis of the dual-motor current signals, the main control unit first performs independent calibration processing on the current signals of the left and right drive motor channels. Zero-point calibration: When the differential steering wheel under test is completely stationary (i.e., neither the left nor right drive motors have current input), the main control unit reads the output voltage values ​​of the left and right Hall current sensors respectively. Ideally, the output voltage should be zero at this time, but due to the aforementioned drift factors, the actual output often has a fixed voltage offset. The main control unit records the zero-point voltage deviation values ​​of the left and right channels respectively, and subtracts the deviation of each channel from all subsequent acquired data to ensure that the feedback values ​​of both channels are zero under zero current conditions. Calibration calibration: Based on the zero-point calibration, the main control unit performs gain calibration on the sensors of the two channels using a known standard current. Specifically, a standard test current of known magnitude can be applied to the motor windings, and the output voltage of the sensor under this standard current is compared with the theoretical voltage to calculate the calibration coefficients for the left and right channels respectively. These calibration coefficients reflect the proportional relationship between the output voltage of each channel sensor and the actual current. Through the above two-stage calibration process, the main control unit substitutes the original acquired voltage values ​​of the left and right channels into the calibration formula to calculate the calibrated left motor current value and calibrated right motor current value after eliminating zero-point offset and gain error.

[0045] After calibrating the current signals of the left and right drive motors, the main control unit calculates two key indicators using the calibrated left and right motor current values: First, current difference calculation. The main control unit calculates the absolute difference between the calibrated left and right motor current values. This difference directly reflects the degree of difference in instantaneous output between the two motors. Under normal operating conditions, the left and right motors of the differential steering wheel should output approximately equal driving forces during the steady-state holding phase (constant load, no steering operation), and the current values ​​of the two motors should remain similar. If the difference is significantly larger, it indicates that one side of the motor is bearing an excessive load or the other side of the motor is underpowered, which may indicate an abnormality in the motor itself, a difference in transmission efficiency, or an abnormality in the differential mechanism. Second, current balance calculation. The main control unit further calculates the current balance, which is the ratio (expressed as a percentage) of the smaller to the larger value of the left and right motor currents. The balance evaluates the cooperative state of the two motors from the perspective of relative proportion. The closer the balance is to 100%, the more balanced the output of the two motors; the lower the balance, the greater the difference in output between the two motors. Compared to current difference, the advantage of balance is its normalization characteristic, which objectively reflects the relative balance of the output of the two motors, unaffected by the absolute current magnitude of the motors. After calculating the two indicators, the main control unit compares them with preset current difference thresholds and balance thresholds. The current difference threshold and balance threshold are pre-set judgment criteria based on the rated parameters and allowable deviation range of the differential steering wheel under test. The current difference threshold specifies the maximum allowable absolute deviation, and the balance threshold specifies the minimum allowable relative balance (e.g., 85%). The judgment logic is OR logic: when the current difference exceeds the current difference threshold, an alarm is triggered, indicating that the absolute output difference between the two motors is too large; when the current balance is lower than the balance threshold, an alarm is also triggered, indicating a serious imbalance in the relative output of the two motors. If either condition is met, it is determined that the output of the two motors is uneven, and the main control unit issues a corresponding abnormality prompt.

[0046] After independently determining the output balance of the two motors, the main control unit further performs in-depth analysis based on a coupled mathematical model. This coupled mathematical model, established during the initial calibration phase, reflects the inherent coupling relationship between three physical quantities—tire deformation, left motor current, and right motor current—when the heavy-duty differential steering wheel is operating normally under healthy conditions. The model is established as follows: when the steering wheel is in a healthy state, synchronously collected data from multiple calibration conditions is used to fit the mapping relationship between the three input variables (tire deformation, left motor current, and right motor current) and the hydraulic load using mathematical methods such as multiple regression. Essentially, the model encapsulates the physical characteristics of a healthy steering wheel; given tire deformation and dual motor current states, each should correspond to a unique theoretical load value when all components of the steering wheel are operating normally. In practice, the main control unit simultaneously substitutes the synchronously collected and calibrated tire deformation feedback signal, the calibrated left motor current value, and the calibrated right motor current value into the coupled mathematical model. The model calculates based on the three input values ​​and outputs the theoretically expected hydraulic load value under this condition. The physical meaning of this theoretical load value is: under the currently measured tire deformation and dual-motor current conditions, the hydraulic load that a healthy heavy-duty differential steering wheel should theoretically output. Essentially, it is a health estimate of the steering wheel's overall condition based on the real-time input of three independent parameters. If all components of the steering wheel are normal, the actual load should be close to this theoretical value; if there is an internal abnormality in the steering wheel, the actual load will deviate from this theoretical value.

[0047] The main control unit compares the theoretical load value with the calibrated real-time load value and calculates the percentage deviation. The calculation logic for this percentage deviation is as follows: divide the absolute value of the difference between the theoretical load value and the calibrated real-time load value by the calibrated real-time load value (or theoretical load value), and then multiply by 100%. This percentage reflects the degree of deviation between the actual physical characteristics of the steering wheel and the health state model. The smaller the deviation, the closer the actual steering wheel's operating characteristics are to the health state model, and the normal operation of all components. The larger the deviation, the more significantly the actual steering wheel's operating characteristics have deviated from the health state, and there may be some internal abnormality. The main control unit compares the calculated percentage deviation with a preset deviation threshold (e.g., 3%). If the percentage deviation exceeds the preset threshold, an abnormality is determined in the steering wheel, and an alarm is triggered. Different internal anomalies can lead to different deviation characteristics: When a tire wears unevenly, the local stiffness characteristics and deformation-load mapping relationship of the tire change. At this time, the theoretical load calculated based on the deformation parameters calibrated in the healthy state will be higher or lower than the actual load, because the same deformation corresponds to different actual loads on unevenly worn tires. When the differential mechanism jams, part of the torque output by the motor is consumed by the jamming resistance, resulting in a decrease in the current-load conversion efficiency. The theoretical load calculated from the two current values ​​input to the model will be higher than the actual load, because part of the motor output is used to overcome the jamming resistance rather than outputting an effective load.

[0048] In some embodiments, the main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model composed of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is then compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, an abnormality is determined in the differential steering wheel, and an alarm is triggered. Specifically, this includes: Zero-point calibration and standardization calibration are performed on the current signals of the left drive motor and the right drive motor respectively using the following formulas: ; ; in, I L，cal This indicates the current value of the left motor after calibration. I R，cal This indicates the current value of the right motor after calibration. K i This represents the calibration coefficient of the current sensor. U L , U R These represent the real-time output voltage values ​​of the left and right motor current acquisition channels, respectively. U i0This is the zero-point voltage value of the current sensor; The current difference is calculated using the following formula: ; Among them, △ I This represents the current difference; The current balance is calculated using the following formula: ; in, This indicates the degree of current balance. min This represents the minimum value. max Indicates the maximum value; The theoretical load value is calculated using the following formula: ; in, F pred represents the theoretical load value, s represents the deformation value corresponding to the tire deformation feedback signal, and a, b, and c represent the coupling coefficients, respectively. The percentage deviation is calculated using the following formula: ; in, This indicates the percentage of deviation. F cal This indicates the real-time load value after calibration.

[0049] Zero-point calibration and standardization are performed on the current signals of the left drive motor and the right drive motor: In the left channel formula, U L The real-time output voltage value of the left motor current acquisition channel, in V, is the raw voltage signal directly read by the main control unit from the left Hall current sensor; U i0 The zero-point voltage value of the current sensor, in V, is the voltage output of the Hall current sensor when there is no current flowing through the left drive motor of the differential steering wheel being measured. Ideally, it should be 0V, but due to factors such as temperature drift, environmental magnetic field interference, and power supply voltage fluctuations, there may be a non-zero offset in reality. K i This is the calibration coefficient for the current sensor, measured in A / V. It is obtained through calibration by applying a known standard test current and reflects the proportional relationship between the change in the sensor's output voltage and the actual change in current. The right channel formula uses the exact same calibration logic and parameter structure: U R This is the real-time output voltage value of the right motor current acquisition channel. K iThe same calibration coefficient is used (the left and right channels use the same model of Hall current sensor and the calibration coefficient is consistent). The calculation logic of both formulas is as follows: First, subtract the zero-point voltage from the real-time output voltage of the sensor to obtain the effective voltage increment after deducting the zero-point drift; then multiply the voltage increment by the calibration coefficient to convert the voltage change into the current change, and obtain the calibrated left motor current value (or the calibrated right motor current value I).

[0050] Calculate the current difference: Subtract the calibrated current value of the left motor from the calibrated current value of the right motor, and take the absolute value. Taking the absolute value ensures the current difference is always non-negative, facilitating subsequent unidirectional comparison with a preset current difference threshold. Regardless of which motor has a larger current, the system only needs to focus on the absolute deviation between the two. The physical meaning of the current difference is the absolute difference in instantaneous output of the two motors. Under normal operating conditions of a heavy-load differential steering wheel, the left and right motors should output approximately equal driving forces during the steady-state holding phase, and the current values ​​of the two motors should remain similar with a small current difference. When the current difference increases significantly, it indicates that one motor is bearing an excessive load or the other motor is underpowered, potentially indicating a malfunction in the motor itself, a difference in transmission efficiency, or a problem with the differential mechanism.

[0051] Calculating current balance: First, compare the current values ​​of the left and right motors to determine the smaller and larger values; then divide the smaller value by the larger value to obtain the ratio between the two; finally, multiply by 100% to convert the ratio into a percentage. Current balance reflects the coordinated state of the dual motor output from a relative proportion perspective. Unlike current difference, balance has the advantage of normalization. Current difference is affected by the absolute current of the motors, and different reference standards exist under different operating conditions (different target loads correspond to different absolute motor current values); while balance reflects the relative balance of the dual motor output as a percentage, unaffected by changes in operating conditions, and has wider applicability. The closer the current balance is to 100%, the more balanced the dual motor output, and the closer the current values ​​of the two motors are; the lower the current balance, the greater the difference in output between the two motors. When the current balance is lower than the preset balance threshold, it indicates a serious imbalance in the relative output of the two motors, and the system determines that the dual motor output is uneven and triggers an alarm.

[0052] Calculating the theoretical load value: a) represents the contribution weight of tire deformation to the load, reflecting the stiffness characteristics of the steering wheel and tire during load bearing. It represents the load change corresponding to each unit change in tire deformation when the dual-motor current remains constant. b) represents the contribution weight of the total current of the dual motors to the load, reflecting the efficiency of converting motor output into a vertical load through the transmission system and differential mechanism. It represents the load change corresponding to each unit change in the total current of the dual motors when tire deformation remains constant. c) is the system zero-drift offset, used to compensate for fixed deviations not included in the model. The theoretical load value is obtained by multiplying the current tire deformation value by the deformation contribution coefficient a, multiplying the sum of the dual-motor currents by the current contribution coefficient b, and then adding the product of these two products to the zero-drift offset c. This formula reflects the inherent coupling relationship between the three key physical quantities of a heavy-duty differential steering wheel under healthy conditions: tire deformation and motor current jointly determine the steering wheel's load bearing state, and there is a clear mapping relationship among the three. When all components of the steering wheel are operating normally, this formula can accurately calculate the corresponding load value based on deformation and current input. However, when an anomaly occurs inside the steering wheel, this mapping relationship is disrupted, and the calculated theoretical load value will deviate from the actual value. The formula uses two independent input variables—deformation and total current of the two motors—to construct the load estimate. Its core significance lies in encapsulating the multi-parameter coupling characteristics of a healthy steering wheel, providing a standardized reference benchmark for subsequent anomaly detection.

[0053] The theoretical load value represents the load performance that the steering wheel should have under healthy conditions (calculated from deformation and current). The calibrated real-time load value represents the actual load performance of the steering wheel at present (measured by pressure sensors). The percentage deviation between the two reflects the degree of deviation between the actual physical characteristics of the steering wheel and the healthy state model. The smaller the percentage deviation, the closer the actual working characteristics of the steering wheel are to the healthy state model, and the normal operation of all components. The larger the percentage deviation, the more significantly the actual working characteristics of the steering wheel have deviated from the healthy state, and there may be some kind of internal abnormality.

[0054] In some embodiments, the hydraulic load closed-loop control system further includes a power supply isolation unit and a data storage and interaction unit, and the method further includes: The power supply isolation unit provides electrical isolation power to the hydraulic load closed-loop control system. AC power is used to provide power to the hydraulic actuator and the main control unit, an independent battery is used to provide drive power to the differential steering wheel under test, and electrical isolation between the power circuit and the signal acquisition circuit is achieved through an isolation transformer and an optocoupler. During the steady-state holding phase, the test data of each acquisition channel is recorded and stored in real time through the data storage and interaction unit. The test data includes the current number of cycles, the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, the current signal of the right drive motor, and the control voltage signal output by the main control unit. The main control unit controls the hydraulic actuator to sequentially execute the loading phase, pressure holding phase, and unloading phase according to the preset automatic cycle durability control logic. After completing a single cycle, the cycle count is updated until the current cycle count equals the target cycle count, at which point the test stops. All test data is then stored in the local storage medium through the data storage and interaction unit.

[0055] In existing hydraulic loading test systems for steering wheels, the power circuit of the hydraulic station, the power supply circuit of the steering wheel under test, and the signal acquisition circuit often share the same power supply system without electrical isolation design. This approach poses a serious hidden danger: the high-power equipment of the hydraulic station generates a large amount of electromagnetic noise during start-up, shutdown, and frequency conversion speed regulation. This noise is conducted along the power supply line to the signal acquisition circuit and control circuit, which may cause glitches and fluctuations in the sensor signals, or even lead to distortion of control signals and program malfunction of the main control unit, seriously affecting the reliability of the test data and the operational reliability of the test system. To address the aforementioned shortcomings, this application implements a dual-path independent power supply architecture through a power supply isolation unit, achieving complete electrical isolation between the power circuit and the signal acquisition circuit: A 380V three-phase AC power supply is used to provide power to the hydraulic actuator (including the hydraulic pump motor, solenoid directional valve, proportional valve, etc.) and the main control unit. This branch bears the energy output task of the entire test system, has a high power demand, and is the energy source for system operation; an independent lithium battery is used to provide drive power to the differential steering wheel under test (configured as 24V or 48V depending on the steering wheel's rated voltage). This battery and the steering wheel under test constitute an independent electrical system, forming a complete power supply circuit with the dual drive motors of the steering wheel under test, and does not share power with other equipment; between the two power supply branches... Electrical isolation between each branch and the signal acquisition circuit is achieved through two core isolation devices: (1) Isolation transformer: An isolation transformer is installed at the AC power supply inlet. Its primary and secondary windings transfer energy through electromagnetic coupling without direct electrical connection, blocking the path of conducted interference from the power grid side into the internal circuit of the system. At the same time, the isolation transformer can also perform preliminary filtering and voltage stabilization of the power supply voltage, reducing high-frequency noise and harmonic interference in the power grid; (2) Optocoupler: An optocoupler is installed in the transmission channel of the control signal and the acquisition signal. Its working principle is to transmit electrical signals using light as a medium. The electrical signal at the input end drives the light-emitting diode to generate an optical signal, and the photosensitive device at the output end receives the optical signal and converts it back into an electrical signal. Since the optical signal is not affected by the electromagnetic field during transmission, the optocoupler completely cuts off the electrical connection between the input and output while realizing effective signal transmission, blocking the path of interference along the signal line.

[0056] This application embodiment utilizes a data storage and interaction unit to record and store test data from each acquisition channel in real time during the steady-state holding phase. The steady-state holding phase is chosen because during loading and unloading, the load is in a dynamic state, resulting in significant data fluctuations and the influence of control transition processes, making it difficult to accurately reflect the load-bearing characteristics of the steering wheel under rated operating conditions. In contrast, during the steady-state holding phase, the load has stabilized near the target value, and the steering wheel is in a stable working state under constant load. The data collected at this time best reflects the performance characteristics of the steering wheel under rated operating conditions and is the most valuable and effective data segment for durability testing. The specific test data recorded includes six categories: (1) Current cycle number: records the cycle number to which the current data belongs, which facilitates the structured organization and horizontal comparison of the data of each cycle, and serves as an index for data tracing and statistical analysis; (2) Hydraulic load feedback signal: reflects the actual load at the current moment, and is the main indicator for evaluating the load-bearing capacity of the steering wheel; (3) Tire deformation feedback signal: reflects the deformation state of the tire under the current load, and is used to analyze the load-bearing characteristics and wear trend of the tire; (4) Left drive motor current signal and (5) Right drive motor current signal: respectively reflect the real-time output status of the two motors, and are used for the balance analysis of the two motors and the status evaluation of the differential mechanism; (6) Control voltage signal output by the main control unit: reflects the adjustment amount output by the control system to maintain the target load, and its changing trend can be used to evaluate the response characteristics of the hydraulic system and the execution effect of the control algorithm.

[0057] This embodiment utilizes the programmable automatic cyclic durability control logic built into the main control unit to control the hydraulic actuator to sequentially execute an automated process of three stages: loading, holding, and unloading. After completing a single cycle of the above three stages, the main control unit increments the cycle count (initially 0) and stores all test data from this cycle (including loading time, data collected from each channel during the holding period, unloading time, etc.) associated with the current cycle count. Subsequently, the main control unit determines whether the current cycle count has reached the target cycle count preset by the tester: if not, it automatically jumps to the loading stage of the next cycle and repeats the complete loading-holding-unloading process without manual intervention; if the target has been reached, it determines that the test task is completed, stops the loading action, and saves all test data completely to the local storage medium through the data storage and interaction unit, while simultaneously outputting a test completion prompt through the human-machine interface.

[0058] In some embodiments, the step of controlling the hydraulic actuator to sequentially execute the loading phase, pressure holding phase, and unloading phase according to a preset automatic cycle durability control logic by the main control unit, and updating the cycle count after completing a single cycle, specifically includes: During the loading phase, the main control unit controls the valve opening of the hydraulic actuator to gradually increase from the initial state at a preset loading speed, so that the measured load rises linearly from zero to the target load, and the actual time consumed during the loading phase is recorded. During the pressure holding phase, the main control unit continuously executes the dual feedback closed-loop adjustment to keep the measured load within the preset error range of the target load and maintain the preset pressure holding duration. During the pressure holding duration, the test data of each acquisition channel are continuously recorded. During the unloading phase, the main control unit controls the valve opening of the hydraulic actuator to gradually decrease at a preset unloading speed, so that the measured load drops from the target load to zero, and the actual time consumed during the unloading phase is recorded. After completing a single loop, the main control unit increments the loop count and determines whether the current loop count has reached the preset target loop count. If it has not reached the target, it automatically enters the loading phase of the next loop; if it has reached the target, it stops the test and triggers a data storage command.

[0059] The loading phase is the initial stage of the automatic cyclic durability control logic. Its core task is to smoothly increase the hydraulic cylinder output load from zero to the preset target load, simulating the working condition of a heavy-duty differential steering wheel gradually bearing vertical loads in actual use. During the loading phase, the main control unit outputs a gradually increasing control voltage to the hydraulic valve group of the hydraulic actuator unit according to preset loading speed parameters, causing the valve opening to gradually increase from the initial state (zero opening or minimum opening). The increase in valve opening gradually increases the flow of hydraulic oil into the hydraulic cylinder, and the hydraulic cylinder output load rises from zero. The preset value of the loading speed (i.e., the increase in load per unit time) is determined based on the load-bearing characteristics of the steering wheel under test and the test standards, and is usually set in mm / s (hydraulic cylinder piston rod extension speed) or kN / s (load change rate). The setting of the loading speed needs to balance test efficiency and protection of the steering wheel under test—too slow a speed results in a long cycle time and low test efficiency; too fast a speed may cause impact damage to the steering wheel, failing to realistically simulate actual working conditions. The main control unit adjusts the valve opening in real time through a dual-feedback closed-loop control algorithm to ensure that the load increases steadily at a preset linear rate, rather than abruptly. This linear increase control method avoids the impact of sudden load changes on the tested steering wheel, while realistically simulating the working scenario of the steering wheel gradually increasing load in actual use. During the loading process, the main control unit continuously records the actual time taken from the start to the end of the loading phase. This time is an important indicator for measuring the dynamic response characteristics and loading control accuracy of the hydraulic system. A significant deviation between the actual and theoretical time may indicate an anomaly in the hydraulic system (such as oil circuit blockage, slow valve response, or insufficient hydraulic pump oil supply). The loading phase terminates when the measured load reaches the target load and meets the stability condition (i.e., the difference between the measured load and the target load is less than a preset difference). At this point, the system automatically enters the pressure holding phase.

[0060] The pressure holding phase is the most crucial stage in the entire automatic cyclic durability control logic. Its task is to continuously bear the target load for a preset time, simulating the continuous operation of a heavy-duty differential steering wheel under rated load. This is a key testing stage for exposing potential defects in the steering wheel. Once the loading phase ends, the measured load has reached the target load, and the stability conditions are met, the system automatically enters the pressure holding phase. The main control unit continuously executes dual-feedback closed-loop regulation, constantly fine-tuning the valve opening through real-time calculations using a PID algorithm to precisely maintain the measured load within the preset error range of the target load. This preset error range is typically expressed as a percentage of the target load (e.g., ±1%FS). Load fluctuations throughout the pressure holding phase are controlled within this preset error range, ensuring that the steering wheel experiences a constant and precise load throughout the entire pressure holding period. The pressure holding duration (typically 10-60 seconds, adjustable via touchscreen) simulates the duration of continuous load borne by the steering wheel in actual use. During this period, the main control unit continuously records test data from each acquisition channel, specifically including the current cycle number, hydraulic load feedback signal (verifying whether the load is maintained within the target range), tire deformation feedback signal (observing the tire's deformation stability under continuous load), left drive motor current signal, and right drive motor current signal (evaluating the output status of the two motors under continuous load), as well as the control voltage signal output by the main control unit (reflecting the adjustment amount continuously output by the control system to maintain load stability). The significance of continuous recording lies in the fact that certain potential defects in the steering wheel (such as slow tire deformation, seal leakage, and progressive differential jamming) may not be significant at the moment of loading, but will gradually be exposed under continuous load. By continuously recording data from each channel during the pressure holding period, the system can capture these abnormal signals that evolve over time, providing more comprehensive data support for fault diagnosis. The termination condition of the pressure holding phase is the end of the pressure holding period, at which point the system automatically transitions to the unloading phase.

[0061] The unloading phase is the final stage of a single cycle. Its task is to smoothly reduce the hydraulic cylinder output load from the target load to zero, completing a full loading-holding-unloading cycle. During the unloading phase, the main control unit controls the valve opening of the hydraulic valve group to gradually decrease according to preset unloading speed parameters, causing a gradual reduction in the hydraulic oil flow into the hydraulic cylinder. Consequently, the hydraulic cylinder output load decreases from the target load until it reaches zero. The unloading speed can be set independently of the loading speed. In actual operating conditions, the dynamic characteristics of the loading and unloading processes of the steering wheel may differ (e.g., there is a hysteresis between the loading deformation curve and the unloading rebound curve of a tire). Independently setting the loading and unloading speeds allows for a more accurate simulation of the loading and unloading characteristics of the steering wheel during actual use. Similar to the loading phase, the main control unit also records the actual time consumed from the start to the end of the unloading phase. Comparing the actual loading time with the actual loading time and the preset theoretical loading time can be used to evaluate the symmetry and consistency of the hydraulic system in both loading and unloading directions. A significant difference between the loading and unloading times may indicate a directional anomaly in the hydraulic system (such as leakage in the check valve or malfunction of the directional valve). The unloading phase terminates when the measured load drops to zero (or a residual value close to zero). At this point, the entire loading-holding-unloading process for one cycle is complete, and the system automatically enters the cycle counting and judgment phase.

[0062] The cycle counting and discrimination phase is the decision-making node of the entire automatic cycle durability control logic. Its task is to count the completed single cycles and determine the subsequent process direction based on the counting results. After the count update is completed, if the current cycle count has not reached the target cycle count, the test task is not yet completed. The main control unit resets the control system state to the initial conditions of the loading phase and automatically jumps to the starting point of the loading phase of the next cycle, repeating the complete loading-holding-unloading process without manual intervention. If the current cycle count has reached the target cycle count, the test task is now complete. The main control unit stops the loading action (closes the hydraulic valve group output) and stores all test data (including data from each stage of all cycles) to the local storage medium through the data storage and interaction unit. At the same time, a test completion prompt is output through the human-machine interface to notify the test personnel that the test is over and the data can be exported and analyzed.

[0063] The above describes the heavy-duty differential steering wheel adaptive hydraulic load closed-loop control method in the embodiments of this application. The computer system in the embodiments of this application will be described in detail below in conjunction with the above-described heavy-duty differential steering wheel adaptive hydraulic load closed-loop control method.

[0064] Please see Figure 3 This is a schematic diagram of an exemplary hardware structure of a computer system in an embodiment of this application.

[0065] In some embodiments, the computer system 300 includes a computer device, which may be a terminal device. The computer device includes a processor 301, a memory 302, a sensor module 303, a communication module 304, an input device 305, and an output device 306 connected via a system bus. The processor 301 of the computer device provides computing and control capabilities. The memory 302 of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database is used to store data.

[0066] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0067] In some embodiments of this application, a computer-readable storage medium is provided, including instructions that, when executed on the computer system 300, cause the computer system 300 to perform the heavy-duty differential steering wheel adaptive hydraulic load closed-loop control method of the embodiments of this application.

[0068] In some embodiments of this application, a computer program product is also provided, which, when run on a computer system 300, causes the computer system 300 to execute the heavy-duty differential steering wheel adaptive hydraulic load closed-loop control method of this application.

[0069] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0070] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive), etc.

[0071] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM or random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for adaptive hydraulic load closed-loop control of a heavy-duty differential steering wheel, characterized in that, An application is made in a hydraulic load closed-loop control system, the hydraulic load closed-loop control system comprising a main control unit, a multi-sensor acquisition unit, and a hydraulic execution unit, the method comprising: Through the synchronous triggering logic of the multi-sensor acquisition unit, the hydraulic load feedback signal of the pressure sensor, the tire deformation feedback signal of the laser displacement sensor, and the current signal of the left drive motor and the right drive motor of the differential steering wheel under test are synchronously acquired at the current moment. The main control unit calculates the change in deformation based on the tire deformation feedback signal and establishes a load prediction model in conjunction with the preset tire stiffness coefficient to obtain the predicted load fluctuation for feedforward compensation. The main control unit uses a preset target load as the control target, the hydraulic load feedback signal as the main feedback, and the predicted load fluctuation as the feedforward compensation amount. It performs dual feedback closed-loop regulation through a PID algorithm and outputs control voltage to adjust the valve opening of the hydraulic actuator until the difference between the measured load and the target load is less than the preset difference and enters the steady-state holding stage. During the steady-state holding phase, the main control unit calculates the current difference and current balance between the current signals of the left drive motor and the right drive motor. The main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model consisting of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, it is determined that there is an abnormality in the differential steering wheel and an alarm is triggered.

2. The method according to claim 1, characterized in that, The process involves using the main control unit with a preset target load as the control target, the hydraulic load feedback signal as the main feedback, and the predicted load fluctuation as the feedforward compensation, to perform dual-feedback closed-loop regulation through a PID algorithm, and outputting a control voltage to adjust the valve opening of the hydraulic actuator. Specifically, this includes: The main control unit performs zero-point calibration and standardization on the hydraulic load feedback signal to eliminate sensor system errors and obtain the calibrated real-time load value. The main control unit calculates the difference between the target load and the calibrated real-time load value as the load control deviation at the current moment. The main control unit inputs the load control deviation into the PID controller for proportional, integral, and derivative operations to obtain the first control component, and multiplies the predicted load fluctuation by a preset feedforward coefficient to obtain the second control component. The main control unit superimposes the first control component and the second control component to generate the final control voltage, which is then output to the hydraulic valve group of the hydraulic actuator to dynamically adjust the valve opening.

3. The method according to claim 2, characterized in that, The process involves using the main control unit with a preset target load as the control target, the hydraulic load feedback signal as the main feedback, and the predicted load fluctuation as the feedforward compensation, to perform dual-feedback closed-loop regulation through a PID algorithm, and outputting a control voltage to adjust the valve opening of the hydraulic actuator. Specifically, this includes: The calibrated real-time load value is calculated using the following formula: ； in, F cal This indicates the real-time load value after calibration. K p This indicates the calibration coefficient of the pressure sensor. I p This indicates the real-time output current value of the pressure sensor. I p0 This indicates the zero-point current value of the pressure sensor. F 0 Indicates the zero-point load offset; The load control deviation is calculated using the following formula: e （ t ）= F set - F cal ； in, e ( t This indicates the load control deviation at the current moment. F set Indicates the target load; The first control component is calculated using the following formula: ； in, U fb ( t ) represents the first control component. , , These are the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively. The second control component is calculated using the following formula: U ff （ t ）= K ff ×△ F pre ； in, U ff ( t ) represents the second control component. K ff This represents the preset feedforward coefficient, Δ F pre This indicates the predicted load fluctuation amount; The final control voltage is calculated using the following formula: U （ t ）= U fb （ t ）+ U ff （ t ）； in, U ( t ) represents the final control voltage.

4. The method according to claim 1, characterized in that, The main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model composed of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, an abnormality is determined in the differential steering wheel, and an alarm is triggered. Specifically, this includes: The main control unit performs zero-point calibration and calibration on the current signals of the left drive motor and the right drive motor respectively to obtain the calibrated current values ​​of the left motor and the right motor. The main control unit calculates the current difference and current balance based on the calibrated left motor current value and the calibrated right motor current value, and compares them with the preset current difference threshold and balance threshold respectively. If the current difference exceeds the current difference threshold or the current balance is lower than the balance threshold, it is determined that the output of the two motors is uneven and an alarm is triggered. The main control unit inputs the tire deformation feedback signal, the calibrated left motor current value, and the calibrated right motor current value at the current moment into the coupled mathematical model to calculate the theoretical load value under the current working condition. The main control unit calculates the percentage deviation between the theoretical load value and the calibrated real-time load value. If the percentage deviation exceeds a preset deviation threshold, it determines that the steering wheel has uneven tire wear or differential mechanism jamming and triggers an alarm.

5. The method according to claim 4, characterized in that, The main control unit calculates the theoretical load value under the current working condition based on a pre-built coupled mathematical model composed of the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, and the current signal of the right drive motor. The theoretical load value is compared with the hydraulic load feedback signal. If the deviation exceeds a set threshold, an abnormality is determined in the differential steering wheel, and an alarm is triggered. Specifically, this includes: Zero-point calibration and standardization calibration are performed on the current signals of the left drive motor and the right drive motor respectively using the following formulas: ； ； in, I L，cal This indicates the current value of the left motor after calibration. I R，cal This indicates the current value of the right motor after calibration. K i This represents the calibration coefficient of the current sensor. U L , U R These represent the real-time output voltage values ​​of the left and right motor current acquisition channels, respectively. U i0 This is the zero-point voltage value of the current sensor; The current difference is calculated using the following formula: ； Among them, △ I This represents the current difference; The current balance is calculated using the following formula: ； in, This indicates the degree of current balance. min This represents the minimum value. max Indicates the maximum value; The theoretical load value is calculated using the following formula: ； in, F pred represents the theoretical load value, s represents the deformation value corresponding to the tire deformation feedback signal, and a, b, and c represent the coupling coefficients, respectively. The percentage deviation is calculated using the following formula: ； in, This indicates the percentage of deviation. F cal This indicates the real-time load value after calibration.

6. The method according to claim 1, characterized in that, The hydraulic load closed-loop control system further includes a power supply isolation unit and a data storage and interaction unit, and the method further includes: The power supply isolation unit provides electrical isolation power to the hydraulic load closed-loop control system. AC power is used to provide power to the hydraulic actuator and the main control unit, an independent battery is used to provide drive power to the differential steering wheel under test, and electrical isolation between the power circuit and the signal acquisition circuit is achieved through an isolation transformer and an optocoupler. During the steady-state holding phase, the test data of each acquisition channel is recorded and stored in real time through the data storage and interaction unit. The test data includes the current number of cycles, the hydraulic load feedback signal, the tire deformation feedback signal, the current signal of the left drive motor, the current signal of the right drive motor, and the control voltage signal output by the main control unit. The main control unit controls the hydraulic actuator to sequentially execute the loading phase, pressure holding phase, and unloading phase according to the preset automatic cycle durability control logic. After completing a single cycle, the cycle count is updated until the current cycle count equals the target cycle count, at which point the test stops. All test data is then stored in the local storage medium through the data storage and interaction unit.

7. The method according to claim 6, characterized in that, The main control unit controls the hydraulic actuator to sequentially execute the loading phase, pressure holding phase, and unloading phase according to a preset automatic cycle durability control logic, and updates the cycle count after completing a single cycle. Specifically, this includes: During the loading phase, the main control unit controls the valve opening of the hydraulic actuator to gradually increase from the initial state at a preset loading speed, so that the measured load rises linearly from zero to the target load, and the actual time consumed during the loading phase is recorded. During the pressure holding phase, the main control unit continuously executes the dual feedback closed-loop adjustment to keep the measured load within the preset error range of the target load and maintain the preset pressure holding duration. During the pressure holding duration, the test data of each acquisition channel are continuously recorded. During the unloading phase, the main control unit controls the valve opening of the hydraulic actuator to gradually decrease at a preset unloading speed, so that the measured load drops from the target load to zero, and the actual time consumed during the unloading phase is recorded. After completing a single loop, the main control unit increments the loop count and determines whether the current loop count has reached the preset target loop count. If it has not reached the target, it automatically enters the loading phase of the next loop; if it has reached the target, it stops the test and triggers a data storage command.

8. A computer system comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-7.

Images