Method and System for Evaluating the Service Life of an Electric Actuator Based on Dynamic Load Monitoring

Abstract

The present invention discloses a method and system for evaluating the service life of an electric actuator based on dynamic load monitoring, specifically relating to the technical field of service life evaluation. Aiming at the cumulative effect of fretting wear caused by the resonance between the load spectrum and mechanical clearance, and the lag in the rupture and reconstruction of the lubricating oil film due to the load change rate exceeding the critical value, the output shaft torque signal is collected and subjected to time-frequency domain conversion to obtain the load change spectrum and the load change rate. Combining with the oil film state monitoring, the risk of lubrication state deterioration and the cumulative effect of wear are evaluated to determine the critical failure risk. When the critical failure risk is lower than the safety threshold, the wear degree is evaluated by finite element analysis of the contact surface stress distribution, and the remaining service life is predicted by combining the failure threshold of the same type of electric actuator in the historical database to judge whether early maintenance or replacement is required, which can accurately reflect the actual wear and failure trend of the electric actuator under multiple working conditions and improve the scientificity of maintenance decision-making and the operating safety.

Description

Technical Field

[0001] The present invention relates to the technical field of life assessment, and more specifically, to a method and system for assessing the life of an electric actuator based on dynamic load monitoring. Background Art

[0002] As a core component in the fields of industrial automation and precision manufacturing, the reliability of an electric actuator directly affects the operation of equipment. Existing life assessment methods are mostly based on linear wear models, without fully considering the non-linear cumulative effect of fretting wear caused by the dynamic load spectrum characteristics and the resonance of mechanical clearances inside the mechanism, as well as the transient deterioration of the lubrication state caused by the hysteresis of the load change rate triggering the rupture and reconstruction of the oil film. In actual situations, load fluctuations and dynamic oil film failure accelerate the wear of the contact surface, seriously shortening the equipment life and posing a great potential safety hazard.

[0003] To solve the above problems, a technical solution is provided. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a method and system for assessing the life of an electric actuator based on dynamic load monitoring to solve the problems raised in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for assessing the life of an electric actuator based on dynamic load monitoring, comprising the following steps:

[0007] Collect the dynamic torque signal of the output shaft of the electric actuator, perform time-frequency domain conversion processing to obtain the load change spectrum and the load change rate;

[0008] Evaluate the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the mechanical clearances inside the electric actuator;

[0009] Monitor the oil film state in the electric actuator, analyze the triggering effect of the load change rate on the dynamic rupture and reconstruction lag phenomenon of the oil film, and evaluate the risk of transient deterioration of the lubrication state;

[0010] Determine the failure critical risk of the electric actuator based on the non-linear cumulative effect of fretting wear and the risk of transient deterioration of the lubrication state;

[0011] When the failure critical risk of the electric actuator is lower than the safety threshold, evaluate the wear degree of the electric actuator by finite element analysis of the stress distribution on the contact surface;

[0012] Based on the wear degree of the electric actuator, combined with the failure thresholds of similar electric actuators in the historical electric actuator operation database, predict the remaining life of the electric actuator and determine whether maintenance or replacement needs to be carried out in advance.

[0013] In a preferred embodiment, collect the dynamic torque signal of the output shaft of the electric actuator, perform time-frequency domain conversion processing to obtain the load change spectrum and the load change rate, specifically:

[0014] Continuously collect the dynamic torque signal of the output shaft of the electric actuator using a torque sensor to obtain the original torque data;

[0015] Perform signal denoising preprocessing on the collected original torque data;

[0016] Process the preprocessed torque signal using the fast Fourier transform to obtain the load change spectrum of the output shaft of the electric actuator;

[0017] Perform numerical differentiation processing on the preprocessed torque signal to obtain the load change rate of the output shaft of the electric actuator.

[0018] In a preferred embodiment, evaluate the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator, specifically:

[0019] Measure the dimensional parameters of the internal mechanical clearance of the electric actuator to obtain the natural frequency of the mechanical clearance;

[0020] Compare the characteristic frequencies in the load change spectrum with the natural frequency of the mechanical clearance to determine the resonance frequency that is the same as the natural frequency of the mechanical clearance;

[0021] Based on the resonance frequency, identify the micro-amplitude relative motion region and the corresponding contact surface of the internal mechanical clearance of the electric actuator in the resonance state;

[0022] Use the motion amplitude and the number of motions of the micro-amplitude relative motion at the contact surface to evaluate the degree of the non-linear cumulative effect of fretting wear.

[0023] In a preferred embodiment, monitor the oil film state in the electric actuator, analyze the triggering effect of the load change rate on the hysteresis phenomenon of oil film dynamic rupture and reconstruction, and evaluate the risk of transient deterioration of the lubrication state, specifically:

[0024] Collect the oil film pressure data during the operation of the electric actuator using an oil film pressure sensor;

[0025] Perform time matching on the oil film pressure data and the load change rate to identify the oil film rupture caused by load fluctuations;

[0026] Record the time when the oil film recovers from the ruptured state to the stable state, which is determined as the duration of oil film reconstruction lag;

[0027] Evaluate the transient deterioration risk of the lubrication state of the electric actuator based on the duration of oil film reconstruction lag and the fluctuation amplitude of the oil film pressure data.

[0028] In a preferred embodiment, based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state, determine the failure critical risk of the electric actuator, specifically:

[0029] When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold, and the deterioration risk parameter is greater than or equal to the deterioration risk parameter threshold, it is determined that the failure critical risk of the electric actuator is lower than the safety threshold; otherwise, it is determined that the failure critical risk of the electric actuator is higher than the safety threshold.

[0030] In a preferred embodiment, when the failure critical risk of the electric actuator is lower than the safety threshold, evaluate the wear degree of the electric actuator by finite element analysis of the stress distribution on the contact surface, specifically:

[0031] Establish a geometric model of the internal mechanical contact surface of the electric actuator;

[0032] Based on the load change spectrum and the load change rate, determine the dynamic load borne by the mechanical contact surface as the load boundary condition for finite element analysis;

[0033] Set the material property parameters for finite element analysis according to the actual elastic modulus, Poisson's ratio and density of the mechanical contact surface material;

[0034] Divide the finite element mesh, apply the dynamic load to the finite element mesh, and perform finite element stress calculation on the mechanical contact surface;

[0035] Obtain the stress distribution nephogram of the mechanical contact surface, determine the maximum stress value and the average stress value on the mechanical contact surface, and calculate the wear degree parameter of the contact surface.

[0036] In a preferred embodiment, based on the wear degree of the electric actuator, combined with the failure threshold of the same type of electric actuator in the historical electric actuator operation database, predict the remaining life of the electric actuator, and determine whether maintenance or replacement needs to be carried out in advance, specifically:

[0037] Obtain the failure threshold of the same type of electric actuator, and use the data interpolation method to calculate the remaining effective operation time of the electric actuator;

[0038] Compare the remaining effective operation time of the electric actuator with the preset safety life to determine whether the electric actuator needs to be maintained or replaced in advance.

[0039] On the other hand, the present invention provides a life evaluation system for an electric actuator based on dynamic load monitoring, including a signal acquisition and processing module, a fretting wear evaluation module, a lubrication state monitoring module, a failure risk evaluation module, a finite element analysis module, and a remaining life prediction module;

[0040] The signal acquisition and processing module collects the dynamic torque signal of the output shaft of the electric actuator, performs time-frequency domain conversion processing, and obtains the load change spectrum and the load change rate;

[0041] The fretting wear evaluation module evaluates the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator;

[0042] The lubrication state monitoring module monitors the oil film state in the electric actuator, analyzes the triggering effect of the load change rate on the hysteresis phenomenon of dynamic rupture and reconstruction of the oil film, and evaluates the transient deterioration risk of the lubrication state;

[0043] The failure risk evaluation module determines the failure critical risk of the electric actuator based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state;

[0044] When the failure critical risk of the electric actuator is lower than the safety threshold, the finite element analysis module evaluates the wear degree of the electric actuator by analyzing the stress distribution of the contact surface through finite element analysis;

[0045] The remaining life prediction module predicts the remaining life of the electric actuator based on the wear degree of the electric actuator, combines the failure thresholds of similar electric actuators in the historical electric actuator operation database, and determines whether maintenance or replacement needs to be carried out in advance.

[0046] Technical effects and advantages of the life evaluation method and system for an electric actuator based on dynamic load monitoring according to the present invention:

[0047] By collecting the output shaft torque signal and obtaining the load change spectrum and rate through time-frequency domain conversion, the non-linear cumulative effect of fretting wear caused by the resonance of the internal mechanical clearance of the mechanism is revealed. At the same time, the oil film pressure state is monitored, the triggering of oil film rupture and the hysteresis of reconstruction caused by load fluctuations are analyzed, and the transient deterioration risk of the lubrication state is evaluated. Based on the fretting wear and lubrication deterioration risks, the failure critical risk is determined. When the failure critical risk is lower than the safety threshold, the wear degree is evaluated by analyzing the stress distribution of the contact surface through finite element analysis. Then, combined with historical operation data and failure thresholds, the remaining life is predicted by interpolation method, and it is timely determined whether maintenance or replacement needs to be carried out in advance, improving the life prediction accuracy, reducing the operation risk, extending the service cycle, and enhancing the safety and economic benefits of the electric actuator. Description of the Drawings

[0048] Figure 1Schematic diagram of the method for evaluating the service life of an electric actuator based on dynamic load monitoring according to the present invention;

[0049] Figure 2 Schematic diagram of the structure of the system for evaluating the service life of an electric actuator based on dynamic load monitoring according to the present invention. Detailed implementation manners

[0050] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0051] Embodiment 1:

[0052] Figure 1 The method for evaluating the service life of an electric actuator based on dynamic load monitoring according to the present invention is given, and it includes the following steps:

[0053] Collect the dynamic torque signal of the output shaft of the electric actuator, perform time-frequency domain conversion processing, and obtain the load change spectrum and the load change rate;

[0054] Evaluate the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator;

[0055] Monitor the oil film state in the electric actuator, analyze the triggering effect of the load change rate on the hysteresis phenomenon of dynamic rupture and reconstruction of the oil film, and evaluate the transient deterioration risk of the lubrication state;

[0056] Based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state, determine the failure critical risk of the electric actuator;

[0057] When the failure critical risk of the electric actuator is lower than the safety threshold, evaluate the wear degree of the electric actuator by finite element analysis of the stress distribution on the contact surface;

[0058] Based on the wear degree of the electric actuator, combined with the failure threshold of the same type of electric actuator in the historical operation database of the electric actuator, predict the remaining life of the electric actuator, and determine whether it is necessary to carry out maintenance or replacement in advance.

[0059] Specifically, collecting the dynamic torque signal of the output shaft of the electric actuator and performing time-frequency domain conversion processing to obtain the load change spectrum and the load change rate includes:

[0060] The dynamic torque signal of the output shaft of the electric actuator is continuously collected by using a torque sensor to obtain the original torque data of a continuous time series: A dynamic torque sensor is installed on the output shaft of the electric actuator. The output end of the dynamic torque sensor is connected to a data acquisition device, and the data acquisition device continuously samples the output signal of the torque sensor at a preset time interval to obtain the original torque data of the time series. The original torque data is defined as: ; where represents the set of torque signals varying with time, which is the set of torque data collected at different time points of the entire output shaft of the electric actuator, reflecting the load conditions received by the output shaft during operation; represents at the sampling moment the torque value, ; represents the total number of sampling points; represents the time variable; represents the index of the sampling point.

[0061] where is the starting sampling moment; represents the sampling time interval. The selection of the sampling interval needs to satisfy the signal sampling theorem to ensure that the highest frequency component does not exceed the Nyquist frequency to avoid aliasing.

[0062] The collected original torque data is preprocessed for signal denoising to obtain the preprocessed torque signal: A moving average filter is used to suppress the random noise and mutation signals in the original torque data to smooth the signal and retain the effective signal components. Then the processed signal is expressed as:

[0063] ; where represents the preprocessed torque signal; After the torque signal is processed by the moving average filter, it can suppress random noise and abnormal interference and retain the main change trend of the signal; represents the number of points in the moving average filter window, that is, the number of sampling points participating in the average calculation before and after the current moment; represents at the sampling moment the torque value; represents the index variable in the summation operation, and its value range is to .

[0064] The preprocessed torque signal is processed by using the fast Fourier transform to obtain the amplitude distribution of the torque signal at different frequencies, and the load change spectrum of the output shaft of the electric actuator is obtained: The preprocessed torque signal is subjected to time-frequency domain conversion processing by using the fast Fourier transform to obtain the load change spectrum. The preprocessed torque signal is , the result of its fast Fourier transform is expressed as:

[0065] ; where represents the Fourier transform result at frequency , that is, the complex representation in the frequency domain, reflecting the complex amplitude of each frequency component in the torque signal, and is used to obtain the amplitude distribution of each frequency component; represents the torque signal after preprocessing at the sampling time ; represents the imaginary unit; represents the frequency variable.

[0066] By taking the modulus of , the load change spectrum is obtained: ; where represents the signal amplitude at frequency .

[0067] The peak frequency and its corresponding amplitude in the load change spectrum are important bases for evaluating the non-linear cumulative effect of fretting wear.

[0068] Perform numerical differentiation on the preprocessed torque signal to obtain the load change rate of the output shaft of the electric actuator: Perform numerical differentiation on the preprocessed torque signal dataset to obtain the load change rate of the output shaft of the electric actuator.

[0069] Define the preprocessed torque signal dataset as: ; where represents the preprocessed torque signal dataset.

[0070] The calculation formula for the load change rate is: ; where represents the load change rate calculated at the sampling time , reflecting the dynamic change speed of the torque signal.

[0071] Specifically, by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator, evaluate the non-linear cumulative effect of fretting wear, including:

[0072] Measure the dimensional parameters of the internal mechanical clearance of the electric actuator to obtain the natural frequency of the mechanical clearance: To evaluate the vibration characteristics of the internal mechanical clearance of the electric actuator, it is necessary to first measure the dimensional parameters of the mechanical clearance and then calculate its natural frequency. The dimensional parameters of the mechanical clearance are obtained through direct measurement, and then the equivalent stiffness and equivalent mass are calculated.

[0073] Define the function for calculating the equivalent stiffness as: ; where Represents the equivalent stiffness of the mechanical clearance; Represents the function for calculating the equivalent stiffness; Represents the actual size parameter of the mechanical clearance; Represents the elastic modulus of the material of the components participating in the vibration analysis.

[0074] Meanwhile, define the function for calculating the equivalent mass as: ; where Represents the equivalent mass related to the mechanical clearance; Represents the function for calculating the equivalent mass; Represents the total mass of the components; Represents the structural distribution parameter, reflecting the mass distribution.

[0075] Using the classical single - degree - of - freedom vibration theory, the natural frequency of the mechanical clearance is expressed by the formula:

[0076] ; where Represents the natural frequency of the mechanical clearance.

[0077] Compare the characteristic frequencies in the load change spectrum with the natural frequency of the mechanical clearance to determine the resonance frequencies that are the same as the natural frequency of the mechanical clearance: Screen out the characteristic frequencies in the load change spectrum that are consistent with the natural frequency of the mechanical clearance. Define the tolerance threshold as , representing the allowable frequency deviation tolerance.

[0078] The resonance frequency determination condition is: , for any frequency in the load change spectrum, if the absolute value of the difference between it and the natural frequency of the mechanical clearance is less than the tolerance threshold, then the frequency is considered to resonate with the mechanical clearance.

[0079] By traversing all the frequencies in the load change spectrum, select the frequencies that meet the conditions as the resonance frequency set, denoted as: ; where Represents the resonance frequency set, containing all the frequencies that meet the resonance conditions.

[0080] Based on the resonance frequencies, identify the micro - amplitude relative motion region and the corresponding contact surfaces of the mechanical clearance inside the electric actuator in the resonance state: After determining the resonance frequencies, use the resonance frequencies to identify the micro - amplitude relative motion region in the mechanical clearance inside the electric actuator caused by resonance. Define that under the resonance condition, the vibration amplitude distribution in the mechanical clearance is expressed by the function: ; where Represents the vibration amplitude at the spatial position ; Represents the function describing the variation of the vibration amplitude with the spatial position; denotes the selected resonance frequency, satisfying ; denotes a certain spatial position of the mechanical contact surface.

[0081] Define the vibration amplitude threshold as , which represents the minimum vibration amplitude threshold for judging the micro-amplitude relative motion.

[0082] According to the vibration amplitude threshold, the identification of the micro-amplitude relative motion region can be expressed as:

[0083] ; where denotes the micro-amplitude relative motion region, which is the set of all positions where the vibration amplitude is greater than the threshold.

[0084] The corresponding contact surface is the actual contact surface of the mechanical components existing in the micro-amplitude relative motion region , and its position and shape are determined by the structural design.

[0085] Utilize the motion amplitude and the number of motions of the micro-amplitude relative motion at the contact surface to evaluate the degree of the non-linear cumulative effect of fretting wear: Based on the micro-amplitude relative motion region under the resonance state and the corresponding contact surface, combine the vibration amplitude and the number of motions to quantitatively evaluate the wear accumulation. Define that at the position , the number of motions of the micro-amplitude relative motion is , which represents the total number of micro-relative motions detected at the position .

[0086] Comprehensively calculate the wear accumulation parameter by using the vibration amplitude and the total number of micro-relative motions. Define the wear accumulation parameter as: ; where denotes the wear accumulation parameter; denotes the number of sampling points included in the micro-amplitude relative motion region.

[0087] By calculating the wear accumulation parameter, the non-linear cumulative effect of wear caused by the micro-amplitude relative motion in the mechanical clearance under the resonance state can be quantitatively evaluated, thereby providing a basis for the mechanism life assessment.

[0088] The larger the wear accumulation parameter is, the more obvious the non-linear cumulative effect of fretting wear inside the electric actuator is. A higher wear accumulation parameter means that during the operation of the electric actuator, due to the resonance of dynamic load and mechanical clearance, both the amplitude and frequency of the micro-scale relative motion generated on the contact surface increase, resulting in a rapid aggravation of local material fatigue damage and surface wear, reflecting a higher degree of structural degradation of key components, and affecting both the overall reliability and remaining life; the larger the wear accumulation parameter is, it indicates that the operating state of the electric actuator deteriorates more, and it is necessary to strengthen monitoring and take maintenance or replacement measures in a timely manner to ensure the safe and stable operation of the equipment.

[0089] Specifically, monitor the oil film state in the electric actuator, analyze the triggering effect of the load change rate on the hysteresis phenomenon of dynamic oil film rupture and reconstruction, and evaluate the risk of transient lubrication state deterioration, including:

[0090] Collect the oil film pressure data during the operation of the electric actuator using an oil film pressure sensor: In the lubrication system of the electric actuator, an oil film pressure sensor is configured to collect the pressure data of the oil film during operation. Set the oil film pressure data as , indicating the oil film pressure value collected at the time point . The sampling time interval of the oil film pressure data is expressed as .

[0091] Perform time matching on the oil film pressure data and the load change rate to identify the oil film rupture caused by load fluctuations: For the time matching of the oil film pressure data and the load change rate, it is necessary to ensure that the sampling time intervals and meet the synchronization requirements or are aligned by interpolation. After matching, analyze the oil film pressure data using the matched time axis to identify the oil film rupture phenomenon caused by load fluctuations.

[0092] Use continuous sampling data to judge the oil film rupture by calculating the difference in oil film pressure between adjacent sampling points. Define the oil film pressure change amount as: ; where represents the oil film pressure change amount from the time point to .

[0093] Preset a pressure change threshold. When the oil film pressure change amount is less than the negative pressure change threshold, it is considered that the oil film has ruptured. At this time is the oil film rupture trigger moment; the pressure change threshold is determined according to experimental data or equipment characteristics.

[0094] Record the time it takes for the oil film to recover from the ruptured state to the stable state, which is determined as the duration of the oil film reconstruction lag: After the oil film ruptures, the oil film pressure data will show a significant drop, and then the oil film will undergo a dynamic reconstruction process until it returns to the stable state. To quantify the oil film reconstruction lag time, it is necessary to record the time from the occurrence of the oil film rupture to the recovery of the oil film pressure to stability.

[0095] Define the stable state pressure as , representing the reference pressure value of the oil film in the stable state.

[0096] Define the allowable deviation as , when the oil film pressure satisfies , it is considered that the oil film has returned to the stable state. At this time, define as the recovery moment.

[0097] Oil film reconstruction lag time Is defined as: ; where, is the oil film reconstruction lag time, indicating the time required for the oil film to recover from the ruptured state to the stable state; is the triggering moment of the oil film rupture; is the moment when the oil film returns to the stable state.

[0098] By recording and statistically analyzing the oil film reconstruction lag time, the distribution of the oil film reconstruction lag time is obtained, providing a quantitative basis for risk assessment.

[0099] Evaluate the transient deterioration risk of the lubrication state of the electric actuator based on the duration of the oil film reconstruction lag and the fluctuation amplitude of the oil film pressure data: To evaluate the transient deterioration risk of the lubrication state of the electric actuator, an oil film pressure fluctuation amplitude parameter is introduced. Define that during the oil film rupture process, the minimum oil film pressure , then the oil film pressure fluctuation amplitude is defined as: ; where, is the oil film pressure fluctuation amplitude, indicating the drop in the oil film pressure from the stable state to the lowest value; represents the minimum pressure value detected during the oil film rupture process.

[0100] Based on the combined influence of the duration of the oil film reconstruction lag and the oil film pressure fluctuation amplitude, construct a deterioration risk parameter, and its calculation formula is: ; where, represents the deterioration risk parameter; is the weight factor, used to adjust the contribution of the oil film reconstruction lag time in risk assessment; is the weight factor, used to adjust the contribution of the oil film pressure fluctuation amplitude in risk assessment. The weight factor and The value of is determined based on experimental verification and the characteristics of the electric actuator.

[0101] The larger the degradation risk parameter, the slower the recovery of the oil film after it breaks during operation, the more severe the oil film pressure fluctuations, and the difficulty of the lubricating oil film to recover to a stable state in time, which leads to a significant reduction in the lubrication effect. A larger degradation risk parameter means that the oil film failure phenomenon is frequent and lasts for a long time, and the local lubrication conditions deteriorate seriously, which increases the friction and accelerates the wear between mechanical parts, reduces the overall operation reliability, and indicates that the electric actuator may be at risk of premature failure.

[0102] Specifically, based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status, the critical failure risk of the electric actuator is determined, including:

[0103] A wear accumulation parameter threshold is preset, and the wear accumulation parameter is compared with the wear accumulation parameter threshold:

[0104] When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold, it indicates that the accumulated degree of micro-motion wear inside the electric actuator has reached or exceeded the critical range, which may cause excessive fatigue of the contact surface or a significant decline in performance. It is necessary to take immediate measures such as maintenance, replacement or enhanced monitoring to avoid further deterioration of key components of the electric actuator;

[0105] When the wear accumulation parameter is less than the wear accumulation parameter threshold, it means that the micro-motion wear is within the critical range and the electric actuator can operate safely within the established working cycle. However, it is still necessary to regularly evaluate the wear development trend and adjust the maintenance strategy in time according to the evaluation results.

[0106] The wear accumulation parameter threshold is determined based on a large amount of actual test data and long-term application experience. By sampling and analyzing the degree of micro-motion wear of the contact surface under different operating conditions, the failure probability of each component under different cumulative wear conditions is summarized, and corrected by combining factors such as material properties, ambient temperature, load spectrum and safety margin, a numerical range reflecting the critical wear level is obtained.

[0107] A degradation risk parameter threshold is preset, and the degradation risk parameter is compared with the degradation risk parameter threshold:

[0108] When the degradation risk parameter is greater than or equal to the degradation risk parameter threshold, it means that the lubricating oil film is frequently broken or rebuilt late due to dynamic load changes, the lubrication state is rapidly deteriorated, and the local lubrication effect is reduced, resulting in increased friction and accelerated wear;

[0109] When the degradation risk parameter is less than the degradation risk parameter threshold, it means that the lubricating oil film recovers quickly and the pressure fluctuation is small, the number of oil film ruptures or the reconstruction lag time is within a controllable range, and the electric actuator can continue to operate according to the regular maintenance plan.

[0110] The threshold of the deterioration risk parameter is obtained through statistical analysis and on-site test verification based on key indicators such as oil film pressure sampling data, oil film reconstruction lag time, and load change rate. Specifically, first, information such as the oil film rupture frequency, minimum pressure value, and recovery duration in different operating stages is collected to evaluate the impact degree on the lubrication system under dynamic conditions. Then, combined with the equipment failure rate and economic considerations in the actual working conditions, the correlation degree and safety boundary among various values are summarized, and the key value that can distinguish normal lubrication from severe deterioration state is selected as the threshold.

[0111] When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold and the deterioration risk parameter is greater than or equal to the deterioration risk parameter threshold, it is determined that the failure critical risk of the electric actuator is lower than the safety threshold; otherwise, it is determined that the failure critical risk of the electric actuator is higher than the safety threshold.

[0112] Specifically, when the failure critical risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element method to evaluate the wear degree of the electric actuator, including:

[0113] Establish the geometric model of the internal mechanical contact surface of the electric actuator: According to the actual measurement data, the geometric model of the internal mechanical contact surface of the electric actuator is constructed, denoted as , representing the spatial region where the mechanical contact surface is located, and its range is determined by the contour and size of the actual components. The set of discrete nodes in the spatial region is denoted as . Each represents the three-dimensional coordinates of the -th node; represents the total number of nodes. The geometric model is obtained through three-dimensional scanning or precise measurement, which can reflect the actual shape and size of the contact surface and provide an accurate basis for finite element mesh generation.

[0114] Based on the load change spectrum and load change rate, determine the dynamic load borne by the mechanical contact surface as the load boundary condition for finite element analysis: According to the load change spectrum and load change rate, determine the dynamic load acting on the mechanical contact surface. Define the dynamic load intensity as: ; where, represents the dynamic load intensity; represents the total number of frequency components ; represents the -th frequency in the load change spectrum; represents the amplitude of the corresponding frequency ;

[0115] The calculated dynamic load intensity is used as the boundary load condition in the finite element analysis, reflecting the dynamic forces borne by the contact surface under actual working conditions, and ensuring that the finite element calculation can truly simulate the load effect.

[0116] Set the material property parameters for the finite element analysis according to the actual elastic modulus, Poisson's ratio, and density of the mechanical contact surface material; set the material property parameters in the finite element analysis according to the actual physical properties of the mechanical contact surface material, including:

[0117] : is the actual elastic modulus of the material, reflecting the stress-strain relationship of the material within the elastic range;

[0118] : is the Poisson's ratio of the material, describing the ratio of the lateral strain to the axial strain of the material when compressed or stretched;

[0119] : is the material density, determining the inertial characteristics of the material.

[0120] The above parameters are obtained through material experiments or data provided by the manufacturer and used as the input of the material properties in the finite element calculation to ensure that the simulation results are consistent with the actual situation.

[0121] Divide the finite element mesh, load the dynamic load onto the finite element mesh, and perform finite element stress calculation on the mechanical contact surface; on the geometric model Perform finite element mesh division on the mechanical contact surface. Divide the geometric model into elements, and the set of them is denoted as ; where represents the element set; is the total number of elements. The shape and size of each element are determined according to the local geometric characteristics of the contact surface to ensure that the mesh size meets the calculation accuracy requirements. Subsequently, load the dynamic load intensity onto the corresponding boundary of the finite element mesh and apply it as the load boundary condition to each element. The finite element method uses the interpolation function between nodes to discretize and solve the entire model, and the stress calculation formula within the element is:

[0122] ; where, represents the stress tensor calculated at node ; is the derivative matrix of the shape function, and its specific form is determined by the selected element type; is the displacement vector at node .

[0123] Solve the entire mesh through the finite element solver to obtain the stress distribution of the contact surface under the dynamic load.

[0124] Obtain the stress distribution nephogram of the mechanical contact surface, extract the stress values at each node position on the mechanical contact surface, and determine the maximum stress value and the average stress value on the mechanical contact surface: After completing the finite element calculation, use numerical visualization technology to generate the stress distribution nephogram of the mechanical contact surface. The stress distribution nephogram intuitively shows the stress value at each node at the location , reflecting the stress concentration area and distribution law. According to the nephogram data, extract the maximum stress value and the average stress value on the mechanical contact surface:

[0125] and ; among them, represents the maximum stress value among all nodes on the mechanical contact surface; represents the average stress value among all nodes on the mechanical contact surface.

[0126] The maximum stress value reflects the local stress concentration situation, while the average stress value describes the overall stress distribution level. Higher maximum stress value and average stress value usually indicate a greater wear risk at the mechanical contact surface, which may cause local fatigue damage.

[0127] Calculate the wear degree parameter of the contact surface according to the maximum stress value and the average stress value on the mechanical contact surface: According to the maximum stress value and the average stress value extracted from the mechanical contact surface, define the wear degree parameter to reflect the difference between local stress concentration and overall stress distribution. Its calculation formula is:

[0128] ; among them, represents the wear degree parameter.

[0129] The larger the wear degree parameter, the more serious the local stress concentration at the key contact surface inside the electric actuator, that is, the more serious the wear degree of the electric actuator. A higher wear degree parameter indicates that significant wear hidden dangers have been accumulated during the long-term operation of the electric actuator, and there is a risk of premature failure.

[0130] Specifically, based on the wear degree of the electric actuator, combined with the failure threshold of the same type of electric actuator in the historical electric actuator operation database, predict the remaining life of the electric actuator, and judge whether it is necessary to carry out maintenance or replacement in advance, including:

[0131] Obtain the failure threshold of the same type of electric actuator, and calculate the remaining effective operation time of the electric actuator by using the data interpolation method: Extract the failure threshold of the same type of electric actuator from the historical electric actuator operation database. Define the failure threshold as , representing the failure threshold, is determined by comprehensively analyzing a large amount of historical data through statistical analysis, material fatigue tests, and engineering experience. It reflects that in actual operation, when the wear accumulation parameter reaches or exceeds the failure threshold, the electric actuator enters the failure state.

[0132] To calculate the remaining effective operating time of the electric actuator, the design life of the electric actuator within the entire life cycle is defined as , representing the expected total operating time of the electric actuator in the new machine state, which is determined based on product design, manufacturer data, or long-term operating experience.

[0133] Based on the data interpolation method, the calculation formula for the remaining effective operating time is:

[0134] ; where represents the remaining effective operating time of the electric actuator.

[0135] Compare the remaining effective operating time of the electric actuator with the preset safety life to determine whether the electric actuator needs to be repaired or replaced in advance:

[0136] Define the preset safety life of the electric actuator, which represents the minimum remaining effective operating time required to ensure safety and reliability during the operation of the electric actuator.

[0137] The comparison rule is:

[0138] When the remaining effective operating time of the electric actuator is greater than or equal to the preset safety life, it is predicted that the remaining life of the electric actuator is sufficient, and the operating state of the electric actuator is within the safe range, and no repair or replacement measures are required;

[0139] When the remaining effective operating time of the electric actuator is less than the preset safety life, it is predicted that the remaining life of the electric actuator is insufficient, and repair or replacement measures are required.

[0140] Embodiment 2:

[0141] The difference between Embodiment 2 and Embodiment 1 of the present invention is that this embodiment introduces the life evaluation system of the electric actuator based on dynamic load monitoring.

[0142] Figure 2 The structural schematic diagram of the life evaluation system of the electric actuator based on dynamic load monitoring of the present invention is given. The life evaluation system of the electric actuator based on dynamic load monitoring includes a signal acquisition and processing module, a fretting wear evaluation module, a lubrication state monitoring module, a failure risk evaluation module, a finite element analysis module, and a remaining life prediction module;

[0143] The signal acquisition and processing module acquires the dynamic torque signal of the output shaft of the electric actuator, performs time-frequency domain conversion processing, and obtains the load change spectrum and the load change rate;

[0144] The fretting wear assessment module evaluates the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator;

[0145] The lubrication state monitoring module monitors the oil film state in the electric actuator, analyzes the triggering effect of the load change rate on the hysteresis phenomenon of dynamic rupture and reconstruction of the oil film, and evaluates the transient deterioration risk of the lubrication state;

[0146] The failure risk assessment module determines the critical failure risk of the electric actuator based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state;

[0147] When the critical failure risk of the electric actuator is lower than the safety threshold, the finite element analysis module evaluates the wear degree of the electric actuator by analyzing the stress distribution of the contact surface through finite element analysis;

[0148] The remaining life prediction module predicts the remaining life of the electric actuator based on the wear degree of the electric actuator, combines the failure threshold of the same type of electric actuator in the historical electric actuator operation database, and determines whether maintenance or replacement needs to be carried out in advance.

[0149] The above formulas are all dimensionless and take their numerical values for calculation. The formulas are obtained by collecting a large amount of data for software simulation to obtain a formula that is closest to the actual situation. The preset parameters and threshold selection in the formulas are set by technicians in the field according to the actual situation.

[0150] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wired (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that contains one or more collections of available media. The available medium can be a magnetic medium (such as a floppy disk, a hard disk, or a magnetic tape), an optical medium (such as a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0151] Those of ordinary skill in the art will appreciate that the modules and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0152] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and modules described above can refer to the corresponding processes in the foregoing method embodiments and will not be described herein again.

[0153] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is only a logical function division, and there can be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings, direct couplings, or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or modules can be in electrical, mechanical, or other forms.

[0154] The module described as a separation component may or may not be physically separated. The component shown as a module may or may not be a physical module, and it may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0155] In addition, in each embodiment of the present application, each functional module can be integrated in a processing module, or each module can exist physically alone, or two or more modules can be integrated in one module.

[0156] If the described function is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0157] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claimed rights.

[0158] Finally: The above is only the preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for evaluating the service life of an electric actuator based on dynamic load monitoring, characterized in that, It includes the following steps: Collect the dynamic torque signal of the output shaft of the electric actuator, perform time-frequency domain conversion processing, and obtain the load change spectrum and the load change rate; Evaluate the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator; Measure the dimensional parameters of the internal mechanical clearance of the electric actuator to obtain the natural frequency of the mechanical clearance; Compare the characteristic frequency in the load change spectrum with the natural frequency of the mechanical clearance to determine the resonance frequency identical to the natural frequency of the mechanical clearance; Based on the resonance frequency, identify the micro-amplitude relative motion region and the corresponding contact surface of the internal mechanical clearance of the electric actuator in the resonance state; Evaluate the degree of the non-linear cumulative effect of fretting wear by using the motion amplitude and the number of motions of the micro-amplitude relative motion at the contact surface; Monitor the oil film state in the electric actuator, analyze the triggering effect of the load change rate on the hysteresis phenomenon of dynamic rupture and reconstruction of the oil film, and evaluate the transient deterioration risk of the lubrication state; Use an oil film pressure sensor to collect the oil film pressure data during the operation of the electric actuator; Perform time matching on the oil film pressure data and the load change rate to identify the oil film rupture caused by load fluctuations; Record the time for the oil film to recover from the ruptured state to the stable state, and determine it as the duration of the oil film reconstruction hysteresis; Evaluate the transient deterioration risk of the lubrication state of the electric actuator based on the duration of the oil film reconstruction hysteresis and the fluctuation amplitude of the oil film pressure data; Determine the failure critical risk of the electric actuator based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state; When the failure critical risk of the electric actuator is lower than the safety threshold, evaluate the wear degree of the electric actuator by finite element analysis of the stress distribution on the contact surface; Based on the wear degree of the electric actuator, combined with the failure threshold of the same type of electric actuator in the historical electric actuator operation database, predict the remaining life of the electric actuator and determine whether maintenance or replacement needs to be carried out in advance.

2. The method for evaluating the service life of an electric actuator based on dynamic load monitoring according to claim 1, wherein Collect the dynamic torque signal of the output shaft of the electric actuator, perform time-frequency domain conversion processing, and obtain the load change spectrum and the load change rate. Specifically: Continuously collect the dynamic torque signal of the output shaft of the electric actuator by using a torque sensor to obtain the original torque data; Perform signal denoising preprocessing on the collected original torque data; Process the preprocessed torque signal by using fast Fourier transform to obtain the load change spectrum of the output shaft of the electric actuator; Perform numerical differentiation processing on the preprocessed torque signal to obtain the load change rate of the output shaft of the electric actuator.

3. The method for evaluating the service life of an electric actuator based on dynamic load monitoring according to claim 2, wherein Determine the failure critical risk of the electric actuator based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state. Specifically: When the wear cumulative parameter is greater than or equal to the wear cumulative parameter threshold and the deterioration risk parameter is greater than or equal to the deterioration risk parameter threshold, it is determined that the failure critical risk of the electric actuator is lower than the safety threshold; otherwise, it is determined that the failure critical risk of the electric actuator is higher than the safety threshold.

4. The method for evaluating the service life of an electric actuator based on dynamic load monitoring according to claim 3, wherein, When the failure critical risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element analysis to evaluate the wear degree of the electric actuator, specifically as follows: Establish the geometric model of the internal mechanical contact surface of the electric actuator; Based on the load change spectrum and the load change rate, determine the dynamic load borne by the mechanical contact surface as the load boundary condition for finite element analysis; Set the material property parameters for finite element analysis according to the actual elastic modulus, Poisson's ratio, and density of the mechanical contact surface material; Divide the finite element mesh, apply the dynamic load to the finite element mesh, and perform finite element stress calculation on the mechanical contact surface; Obtain the stress distribution contour map of the mechanical contact surface, determine the maximum stress value and the average stress value on the mechanical contact surface, and calculate the wear degree parameter of the contact surface.

5. The method for evaluating the service life of an electric actuator based on dynamic load monitoring according to claim 4, wherein, Based on the wear degree of the electric actuator, combined with the failure threshold of similar electric actuators in the historical electric actuator operation database, predict the remaining life of the electric actuator and determine whether maintenance or replacement needs to be carried out in advance, specifically as follows: Obtain the failure threshold of similar electric actuators and calculate the remaining effective operation time of the electric actuator using the data interpolation method; Compare the remaining effective operation time of the electric actuator with the preset safety life to determine whether the electric actuator needs to be maintained or replaced in advance.

6. A life assessment system for an electric actuator based on dynamic load monitoring, which is used to implement the life assessment method for an electric actuator based on dynamic load monitoring according to any one of claims 1-5, characterized in that, It includes a signal acquisition and processing module, a fretting wear evaluation module, a lubrication state monitoring module, a failure risk assessment module, a finite element analysis module, and a remaining life prediction module; The signal acquisition and processing module acquires the dynamic torque signal of the output shaft of the electric actuator, performs time-frequency domain conversion processing, and obtains the load change spectrum and the load change rate; The fretting wear evaluation module evaluates the non-linear cumulative effect of fretting wear by analyzing the load change spectrum and the resonance response of the internal mechanical clearance of the electric actuator; Measure the dimensional parameters of the internal mechanical clearance of the electric actuator to obtain the natural frequency of the mechanical clearance; Compare the characteristic frequencies in the load change spectrum with the natural frequency of the mechanical clearance to determine the resonance frequency identical to the natural frequency of the mechanical clearance; Based on the resonance frequency, identify the micro-amplitude relative motion region and the corresponding contact surface of the internal mechanical clearance of the electric actuator in the resonance state; Use the motion amplitude and the number of motions of the micro-amplitude relative motion at the contact surface to evaluate the degree of the non-linear cumulative effect of fretting wear; The lubrication state monitoring module monitors the oil film state in the electric actuator, analyzes the triggering effect of the load change rate on the hysteresis phenomenon of the dynamic rupture and reconstruction of the oil film, and evaluates the transient deterioration risk of the lubrication state; Use the oil film pressure sensor to collect the oil film pressure data during the operation of the electric actuator; Perform time matching on the oil film pressure data and the load change rate to identify the oil film rupture caused by load fluctuations; Record the time for the oil film to recover from the rupture state to the stable state, which is determined as the duration of the oil film reconstruction lag; Evaluate the transient deterioration risk of the lubrication state of the electric actuator based on the duration of the oil film reconstruction lag and the fluctuation amplitude of the oil film pressure data; The failure risk assessment module determines the failure critical risk of the electric actuator based on the non-linear cumulative effect of fretting wear and the transient deterioration risk of the lubrication state; When the failure critical risk of the electric actuator is lower than the safety threshold, the finite element analysis module evaluates the wear degree of the electric actuator by analyzing the stress distribution of the contact surface through finite element analysis; Based on the wear degree of the electric actuator and combining with the failure thresholds of similar electric actuators in the historical operation database of electric actuators, the remaining life prediction module predicts the remaining life of the electric actuator and determines whether maintenance or replacement needs to be carried out in advance.

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