Suspension stiffness and damping collaborative control method and system for electric all-terrain vehicle

Abstract

The present application relates to electric all-terrain vehicle suspension control technical field, especially to a kind of electric all-terrain vehicle suspension stiffness and damping collaborative control method and system.The present application is normalized to air spring acoustic emission response by mechanical workload, combined with the degree of suspension movement and the degree of electric drive load to construct nonlinear interaction, identify the critical approaching state of air bag fatigue damage, obtain air spring predicted stiffness and stiffness deviation, dynamically limit stiffness adjustment range and determine the compression damping and rebound damping of shock absorber.The present application can identify the change of internal fatigue state before the significant change of air spring macroscopic performance, reduce the interference of complex operating conditions on state judgment, improve the matching degree between air spring load characteristics and shock absorber damping parameters, and enhance the stability, adaptive ability and operation reliability of suspension control under continuous high frequency, large stroke obstacle and complex non-paved road.

Description

Technical Field

[0001] This invention relates to the field of suspension control technology for electric all-terrain vehicles, and in particular to a method and system for coordinated control of suspension stiffness and damping of electric all-terrain vehicles. Background Technology

[0002] During the operation of an electric all-terrain vehicle, the suspension needs to continuously adjust its load-bearing stiffness and damping based on vehicle load, road surface undulations, and vehicle motion. Existing technology determines the target stiffness of the air spring and the compression and rebound damping of the shock absorber based on air spring pressure, suspension height, suspension displacement, suspension speed, vehicle vertical acceleration, and vehicle speed. However, during continuous high-frequency, long-stroke obstacle crossing, the air spring airbag load-bearing composite layer will be subjected to continuous alternating loads, and microcracks and interface debonding will gradually appear inside. Before obvious air leakage occurs, the air spring pressure and suspension height are within the normal range, but the load-bearing capacity inside the airbag has already begun to change. This type of damage is insidious and gradual, making it difficult to identify through conventional operating parameters. This leads to a deviation between the stiffness and damping parameters determined based on the health status and the actual load-bearing state of the air spring.

[0003] Existing technologies in suspension control primarily rely on pressure, displacement, and vehicle dynamic response to adjust target stiffness and damping, making it difficult to detect internal fatigue damage in the air spring in its early stages. Methods that estimate air spring stiffness using vehicle vibration response are easily affected by road surface excitation, vehicle load, and changes in operating conditions, making it difficult to identify the critical approach state of internal fatigue damage before significant changes in the macroscopic stiffness of the air spring. Current control methods match damper damping to the target stiffness under healthy conditions, making it difficult to coordinate the adjustment range of stiffness, compression, and rebound damping based on changes in the actual load-bearing capacity of the air spring, and thus failing to consider the suspension motion characteristics of electric all-terrain vehicles during driving slip and continuous obstacle crossing. Summary of the Invention

[0004] To overcome the shortcomings of suspension control in timely identifying fatigue damage inside airbags and coordinating stiffness and damping adjustment, this invention provides a method and system for coordinated control of suspension stiffness and damping in electric all-terrain vehicles.

[0005] The technical implementation scheme of the present invention is as follows: a method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle, comprising the following steps:

[0006] S1: Acquire instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed. Define the time interval between two adjacent identical suspension mid-states as a suspension working cycle.

[0007] S2: Calculate the air spring bearing capacity based on the instantaneous value of the air spring pressure and the effective bearing area of ​​the air spring. Integrate the absolute value of the product of the air spring bearing capacity and the instantaneous value of the suspension speed within one suspension working cycle to obtain the mechanical workload of the air spring. Process the original acoustic emission signal to obtain the acoustic emission response per unit mechanical workload and the degree of acoustic emission event activity per unit time.

[0008] S3: Construct the nonlinear interaction quantity before the critical acoustic emission based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load. Determine the critical approximation result of airbag fatigue damage based on the changing trend of the nonlinear interaction quantity before the critical acoustic emission of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles.

[0009] S4: Based on the critical approximation results of airbag fatigue damage and the calibration relationship of healthy air spring test bench, predict the effective stiffness and predicted stiffness deviation of air spring;

[0010] S5: Based on the predicted stiffness deviation, limit the target stiffness adjustment range of the air spring, redetermine the target values ​​of the shock absorber compression damping and rebound damping, and use the instantaneous value of the vehicle body vertical acceleration to perform closed-loop correction on the target values ​​of the shock absorber compression damping and rebound damping.

[0011] Preferably, the acquisition of instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed, defining the time interval between two adjacent identical suspension neutral states as a suspension working cycle, includes: setting an acoustic emission sensor on the outer surface of the air spring airbag; setting a pressure sensor and a temperature sensor in the air spring air circuit; setting a suspension displacement sensor in the suspension mechanism; setting a vertical acceleration sensor on the vehicle body; and setting a wheel angular velocity sensor on the wheel. The system includes a speed sensor to obtain instantaneous vehicle speed from the vehicle controller, and instantaneous motor torque and angular velocity from the drive motor controller. An acoustic emission sensor is used to acquire raw acoustic emission signals. A pressure sensor is used to acquire instantaneous air spring pressure, a temperature sensor is used to acquire instantaneous airbag temperature, a suspension displacement sensor is used to acquire instantaneous suspension displacement, a vertical acceleration sensor is used to acquire instantaneous vehicle vertical acceleration, and a wheel angular velocity sensor is used to acquire instantaneous wheel angular velocity. The instantaneous suspension speed is obtained by time differentiation of the instantaneous suspension displacement values.

[0012] Preferably, the step of calculating the air spring load-bearing capacity based on the instantaneous value of the air spring pressure and the effective load-bearing area of ​​the air spring, and integrating the absolute value of the product of the air spring load-bearing capacity and the instantaneous value of the suspension speed within one suspension working cycle to obtain the mechanical workload of the air spring, includes: air spring load-bearing capacity. The calculation formula is: ,in This is the instantaneous value of the air spring pressure. To be based on the instantaneous value of suspension displacement Determined effective load-bearing area of ​​the air spring; mechanical workload of the air spring. The calculation formula is: ,in For the first One suspension working cycle, For the instantaneous value of the suspension speed; for the first Each suspension work cycle, including the first The most recent continuous suspension work cycle, including the last one. Each suspension work cycle constitutes a sliding window, and the suspension work cycle number within the sliding window... for arrive For the instantaneous values ​​of suspension speed, calculate the peak value according to the suspension working cycle, sum the peak values ​​of suspension speed for each suspension working cycle within the sliding window, and then divide by . The average peak value of the suspension speed was obtained. .

[0013] Preferably, the process of processing the raw acoustic emission signal to obtain the acoustic emission response per unit mechanical workload and the activity level of the acoustic emission event per unit time includes: processing the raw acoustic emission signal... Bandwidth filtering is performed to obtain the acoustic emission filtered signal. ; Filter the acoustic emission signal The acoustic emission filtered signal is compared with a preset amplitude threshold. An acoustic emission event is formed within a continuous time period exceeding a preset amplitude threshold; the number of events is statistically analyzed. The number of acoustic emission events generated within each suspension working cycle is used to obtain the acoustic emission event count. ; Filtering of acoustic emission signals In the One suspension working cycle By performing square integration within the inner quadratic region, the acoustic emission signal energy is obtained. According to the preset reference mechanical workload and preset reference acoustic emission signal energy Normalization is performed to obtain and ,in, To normalize the mechanical workload of the air spring, Normalized acoustic emission signal energy; acoustic emission response per unit mechanical workload The calculation formula is: The degree of acoustic emission event activity per unit time The calculation formula is: ,in For the first The length of time for each suspension working cycle This is the preset reference frequency.

[0014] Preferably, the step of constructing the pre-critical nonlinear interaction quantity of acoustic emission based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load includes: obtaining the drive wheel number. For the first Each drive wheel, based on a pre-calibrated effective wheel radius. Instantaneous value of wheel angular velocity Calculate the linear velocity of the wheel The formula is: Based on the instantaneous value of vehicle speed Calculate wheel drive slip ratio The formula is: ,in To preset the low-speed protection value; based on the instantaneous value of the motor torque. and instantaneous value of motor angular velocity Calculate the power of the driving machinery ; Calculate the first Average drive mechanical power per suspension working cycle The formula is: A moving average was applied to the acoustic emission response per unit of mechanical workload and the activity level of acoustic emission events per unit time to obtain... and ,in For the first Acoustic emission response per unit mechanical workload of a suspension work cycle. For the first The degree of acoustic emission activity per unit time in each suspension work cycle; calculation of suspension motion. The formula is: ,in This represents the average peak value of the suspension speed. Preset reference suspension speed; calculate the deviation of acoustic emission response per unit mechanical workload. The formula is: ,in The acoustic emission response of a healthy air spring under the same mechanical working conditions is determined by a pre-calibrated reference unit of mechanical workload; the deviation of the acoustic emission event activity level per unit time is calculated. The formula is: ,in The degree of acoustic emission event activity per unit time is pre-calibrated for a healthy air spring under the same mechanical working conditions; the degree of electric drive load is calculated. The formula is: ,in Preset reference driving mechanical power; calculate nonlinear interaction quantities before acoustic emission criticality. The formula is: ,in , , and The weighting coefficients for the nonlinear interaction quantities before the critical acoustic emission threshold.

[0015] Preferably, determining the critical approximation result of airbag fatigue damage based on the trend of changes in the nonlinear interaction quantity before the critical acoustic emission of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles includes: calculating the changes in the nonlinear interaction quantity between adjacent suspension working cycles. The formula is: ,in For the first The acoustic emission pre-critical nonlinear interaction quantity of each suspension working cycle; constructing the pre-critical change quantity. The formula is: In recent times In each suspension working cycle, the statistics satisfy... Suspension duty cycle ratio The formula is: ,in For indicator functions, Preset threshold for change before criticality; critical approximation index for airbag fatigue damage. The calculation formula is: ,in For preset weighting coefficients; when And from the first A preset number of suspension working cycles are continuously advanced forward by one suspension working cycle. satisfy At that time, it was determined that the fatigue damage inside the load-bearing composite layer of the air spring airbag had entered the pre-critical evolution state. For the first The critical approach index for airbag fatigue damage per suspension working cycle. This is a preset threshold before the critical point.

[0016] Preferably, the step of predicting the effective stiffness and predicted stiffness deviation of the air spring based on the critical approximation results of air spring fatigue damage and the calibration relationship of the healthy air spring bench includes: obtaining a healthy target stiffness mapping function by performing stiffness calibration on different combinations of instantaneous air spring pressure values, different instantaneous air spring temperature values, and different instantaneous suspension displacement values. Based on the instantaneous value of the air spring pressure Instantaneous airbag temperature and instantaneous value of suspension displacement The current target stiffness of the air spring was obtained by using the calibration relationship of the healthy air spring test bench. The formula is: Based on the critical approximation index of airbag fatigue damage Calculate and predict the effective stiffness of the air spring The formula is: ,in To predict the effective stiffness sensitivity coefficient; to predict stiffness deviation The calculation formula is: .

[0017] Preferably, the step of redetermining the target values ​​of the damper compression damping and rebound damping based on the predicted stiffness deviation limiting the target stiffness adjustment range of the air spring includes: the upper limit of the target stiffness of the air spring. The calculation formula is: ,in This represents the upper limit of the initial target stiffness of the air spring. The upper limit of the target stiffness of the air spring is the compression coefficient; the target value of the damper's compression damping is... The calculation formula is: ,in Basic compression damping, This is the gain coefficient for the compression damping stiffness deviation. This is the compression damping velocity correction factor; the slip factor calculation formula is: ,in The preset reference slip ratio is used; the formula for calculating the target value of the shock absorber's rebound damping is: ,in Based on rebound damping, This is the gain coefficient for rebound damping stiffness deviation. This is the rebound damping speed correction coefficient.

[0018] Preferably, the closed-loop correction of the target values ​​of the shock absorber compression damping and rebound damping using the instantaneous value of the vehicle body vertical acceleration includes: calculating the current actual vehicle body vibration response. The formula is: ,in The instantaneous value of the vehicle's vertical acceleration; the root mean square value of the preset reference vehicle's vertical acceleration. The damping is corrected using a closed-loop method based on the baseline to obtain the final target damping. ,in This is the target damping for the current suspension phase; when the suspension is currently in the compression phase... Target value for compression damping of the shock absorber When the suspension is currently in the rebound phase, The target value for the rebound damping of the shock absorber ; The gain coefficient is corrected for the damping closed loop; when the airbag fatigue damage critically approaches the index. Less than the preset critical threshold At the same time, maintain the normal target stiffness adjustment range of the air spring, and the control range of the compression damping and rebound damping of the shock absorber; when Greater than the preset critical threshold Then, the target stiffness adjustment range of the air spring is limited, and the target values ​​of the shock absorber compression damping and rebound damping are re-determined based on the predicted stiffness deviation. Closed-loop correction is performed using the instantaneous value of the vehicle body's vertical acceleration. Restore to the preset release threshold During the following preset number of suspension work cycles, the normal air spring target stiffness adjustment range and shock absorber compression damping and rebound damping control range are restored; among which... This is the preset release threshold.

[0019] Preferably, a suspension stiffness and damping coordinated control system for an electric all-terrain vehicle further includes:

[0020] The suspension operation data acquisition module is used to acquire instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed. The time interval between two adjacent identical suspension mid-states is defined as a suspension working cycle.

[0021] The mechanical workload calculation module is used to calculate the air spring bearing capacity based on the instantaneous value of the air spring pressure and the effective bearing area of ​​the air spring. Within one suspension working cycle, the absolute value of the product of the air spring bearing capacity and the instantaneous value of the suspension speed is integrated to obtain the mechanical workload of the air spring. The original acoustic emission signal is processed to obtain the acoustic emission response per unit mechanical workload and the degree of acoustic emission event activity per unit time.

[0022] The acoustic emission critical identification module is used to construct the nonlinear interaction quantity before the acoustic emission criticality based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load. Based on the changing trend of the nonlinear interaction quantity before the acoustic emission criticality of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles, the critical approximation result of airbag fatigue damage is determined.

[0023] The air spring stiffness prediction module is used to predict the effective stiffness and predicted stiffness deviation of the air spring based on the critical approximation results of airbag fatigue damage and the calibration relationship of healthy air spring bench.

[0024] The stiffness-damping coordinated control module is used to limit the target stiffness adjustment range of the air spring based on the predicted stiffness deviation, redetermine the target values ​​of the shock absorber compression damping and rebound damping, and use the instantaneous value of the vehicle body vertical acceleration to perform closed-loop correction on the target values ​​of the shock absorber compression damping and rebound damping.

[0025] Beneficial Effects: This invention acquires information on air spring pressure, airbag temperature, suspension motion, acoustic emission, and vehicle drive status. It normalizes the acoustic emission response caused by fatigue damage to the airbag bearing composite layer according to the mechanical workload of the air spring. By combining the activity level of the acoustic emission event, the degree of suspension motion, and the degree of electric drive load, a nonlinear interaction relationship is constructed, enabling indirect identification of the critical approach state of airbag fatigue damage. Furthermore, by utilizing the calibration relationship of healthy air spring test benches, the critical approach index of airbag fatigue damage is further mapped to the predicted effective stiffness and predicted stiffness deviation of the air spring. This allows the internal fatigue state, which is difficult to measure directly, to be transformed into stiffness change information that can be used for suspension control, enabling early judgment before significant changes in the macroscopic stiffness of the air spring. By simultaneously using the predicted stiffness deviation to limit the target stiffness adjustment of the air spring... The system re-determines the range and re-establishes the compression and rebound damping of the shock absorber, and corrects the rebound damping based on wheel slippage conditions. This enables a linkage control between changes in air spring load capacity and shock absorber damping adjustment, avoiding continued stiffness and damping matching based on healthy state parameters. By utilizing the vehicle's vertical acceleration to perform closed-loop correction of compression and rebound damping, the predictive control results can be dynamically adjusted based on the actual vehicle vibration response, improving control adaptability under complex unpaved road conditions and continuous obstacle crossing. By sequentially linking acoustic emission damage characterization, mechanical workload normalization, nonlinear critical identification, effective stiffness prediction, and stiffness-damping coordinated control, a continuous technology chain is formed, from internal damage perception to suspension parameter reconstruction and then to vehicle dynamic response feedback. Each link addresses state identification, stiffness prediction, and control matching issues respectively. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to the present invention.

[0027] Figure 2 This is a schematic diagram of the structure of a suspension stiffness and damping coordinated control system for an electric all-terrain vehicle according to the present invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: A method for coordinated control of suspension stiffness and damping in an electric all-terrain vehicle, such as... Figure 1 As shown, it includes the following steps:

[0030] S1: Acquire instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed. Define the time interval between two adjacent identical suspension mid-states as a suspension working cycle.

[0031] S2: Calculate the air spring bearing capacity based on the instantaneous value of the air spring pressure and the effective bearing area of ​​the air spring. Integrate the absolute value of the product of the air spring bearing capacity and the instantaneous value of the suspension speed within one suspension working cycle to obtain the mechanical workload of the air spring. Process the original acoustic emission signal to obtain the acoustic emission response per unit mechanical workload and the degree of acoustic emission event activity per unit time.

[0032] S3: Construct the nonlinear interaction quantity before the critical acoustic emission based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load. Determine the critical approximation result of airbag fatigue damage based on the changing trend of the nonlinear interaction quantity before the critical acoustic emission of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles.

[0033] S4: Based on the critical approximation results of airbag fatigue damage and the calibration relationship of healthy air spring test bench, predict the effective stiffness and predicted stiffness deviation of air spring;

[0034] S5: Based on the predicted stiffness deviation, limit the target stiffness adjustment range of the air spring, redetermine the target values ​​of the shock absorber compression damping and rebound damping, and use the instantaneous value of the vehicle body vertical acceleration to perform closed-loop correction on the target values ​​of the shock absorber compression damping and rebound damping.

[0035] An acoustic emission sensor is installed on the outer surface of the air spring airbag; a pressure sensor and a temperature sensor are installed in the air spring air circuit; a suspension displacement sensor is installed in the suspension mechanism; a vertical acceleration sensor is installed on the vehicle body; and a wheel angular velocity sensor is installed on the wheel. Instantaneous vehicle speed values ​​are obtained from the vehicle controller, and instantaneous motor torque and instantaneous motor angular velocity values ​​are obtained from the drive motor controller. The acoustic emission sensor is used to acquire the raw acoustic emission signal; the pressure sensor is used to acquire the instantaneous air spring pressure value; the temperature sensor is used to acquire the instantaneous airbag temperature value; the suspension displacement sensor is used to acquire the instantaneous suspension displacement value; the vertical acceleration sensor is used to acquire the instantaneous vehicle body vertical acceleration value; and the wheel angular velocity sensor is used to acquire the instantaneous wheel angular velocity value. The instantaneous suspension speed value is obtained by time differentiation of the instantaneous suspension displacement value.

[0036] It should be explained that the acoustic emission sensor is arranged on the outer surface of the air spring airbag. The installation position is determined by calibrating the acoustic emission detectable area on the outer surface of the airbag. Candidate positions are selected on the outer surface of the air spring airbag. An acoustic emission simulation source is used to apply excitation to the corresponding area of ​​the airbag bearing composite layer. The acoustic emission response signal at each candidate position is collected. The amplitude of the acoustic emission response signal during excitation is compared with the amplitude of the background noise after excitation stops. The candidate position area with the largest ratio of the acoustic emission response signal amplitude during excitation to the background noise amplitude after excitation stops is determined as the acoustic emission detectable area on the outer surface of the airbag. The acoustic emission sensor is arranged in the acoustic emission detectable area on the outer surface of the airbag, so that the acoustic emission sensor couples with the elastic wave generated by the alternating strain of the airbag bearing composite layer. The pressure sensor and the temperature sensor are connected to the air spring air circuit to obtain the instantaneous values ​​of the air spring pressure and the airbag temperature, respectively. The suspension displacement sensor is installed on the suspension mechanism, and the range and installation direction are based on the suspension design stroke. The suspension displacement sensor's range covers the entire designed travel of the suspension from its maximum compression position to its maximum rebound position, and its installation direction is set along the displacement measurement direction of the suspension mechanism, ensuring a monotonic correspondence between the sensor's output signal and the instantaneous suspension displacement value. The vertical acceleration sensor is fixed to the vehicle body, with its sensitive axis perpendicular to the vehicle body. The wheel angular velocity sensor is mounted at the wheel hub, coaxially with the wheel, ensuring its detection axis aligns with the wheel's rotation axis. The acoustic emission sensor acquires the raw acoustic emission signal, the suspension displacement sensor acquires the instantaneous suspension displacement value, the vertical acceleration sensor acquires the instantaneous vehicle body vertical acceleration value, and the wheel angular velocity sensor acquires the instantaneous wheel angular velocity value. The instantaneous vehicle speed value is read from the vehicle controller, and the instantaneous motor torque and angular velocity values ​​are read from the drive motor controller, or... Calculate the instantaneous value of the motor's angular velocity, where For the first The instantaneous angular velocity of each drive motor, in rad / s. For the first The speed of the drive motor is expressed in r / min; the instantaneous value of the suspension speed is obtained by differentiating the instantaneous value of the suspension displacement over time, using the following formula: Discrete form is , The instantaneous value of the suspension displacement is expressed in meters (m). The instantaneous value of the suspension speed is given in m / s. and For adjacent sampling times, The time difference between adjacent sampling moments is expressed in seconds. Spectral analysis is performed on the instantaneous suspension displacement value to obtain the main frequency range of suspension motion. According to the Nyquist sampling theorem, the sampling frequency should not be less than twice the highest frequency in the main frequency range of suspension motion. The sampling frequency of the instantaneous suspension displacement value is determined, and the low-pass filter cutoff frequency is set to be no higher than half the sampling frequency and no lower than the highest frequency in the main frequency range of suspension motion. This filters the instantaneous suspension speed value and suppresses differential noise. All sensor data are synchronized with the vehicle controller timescale. Outlier values ​​are removed and missing values ​​are marked according to sensor range, signal change rate, and sampling period. This ensures that the instantaneous values ​​of the air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, and acoustic emission are synchronized. The initial signal, the instantaneous value of the wheel angular velocity, the instantaneous value of the motor torque, the instantaneous value of the motor angular velocity, and the instantaneous value of the vehicle speed all have the same time reference; the healthy air spring refers to an air spring that meets the design requirements after visual inspection, airtightness inspection, and static stiffness inspection, and does not show cracks, debonding, or abnormal stiffness changes in the load-bearing composite layer within the specified number of fatigue tests; the known fatigue-damaged air spring refers to an air spring that has been confirmed to have a known degree of fatigue damage after fatigue testing through a preset number of fatigue cycles or a preset fatigue load, and through disassembly inspection, non-destructive testing, or stiffness change detection; the pre-critical fatigue evolution state refers to the air spring whose internal load-bearing composite layer has shown detectable fatigue evolution characteristics, but has not yet experienced a macroscopic failure state that affects normal airtightness and basic load-bearing function;

[0037] When calibrating the parameters, reference mechanical working conditions are first established. These conditions include air spring pressure, airbag temperature, suspension displacement amplitude, suspension speed peak value, and drive mechanical power, which are divided into multiple working condition intervals according to the actual operating range of the electric all-terrain vehicle. For each working condition interval, multiple suspension working cycles are continuously collected on a healthy air spring, and the corresponding cycle data are obtained according to the calculation methods of air spring mechanical workload, acoustic emission response per unit mechanical workload, acoustic emission event activity per unit time, suspension speed peak value, and drive mechanical power in this embodiment. When a new suspension working cycle is added, if the change in the arithmetic mean of the corresponding statistic is less than the standard deviation of the measurement noise of the statistic, the corresponding reference statistic is considered to have reached a stable state, and the stable arithmetic mean is used as the corresponding reference parameter.

[0038] Air spring load capacity The calculation formula is: ,in This is the instantaneous value of the air spring pressure. To be based on the instantaneous value of suspension displacement Determined effective load-bearing area of ​​the air spring; mechanical workload of the air spring. The calculation formula is: ,in For the first One suspension working cycle, For the instantaneous value of the suspension speed; for the first Each suspension work cycle, including the first The most recent continuous suspension work cycle, including the last one. Each suspension work cycle constitutes a sliding window, and the suspension work cycle number within the sliding window... for arrive For the instantaneous values ​​of suspension speed, calculate the peak value according to the suspension working cycle, sum the peak values ​​of suspension speed for each suspension working cycle within the sliding window, and then divide by . The average peak value of the suspension speed was obtained. .

[0039] It should be explained that the air spring's load-bearing capacity... The instantaneous value of the air spring pressure With respect to the effective bearing area of ​​the air spring according to Multiply to obtain the instantaneous value of the air spring pressure. The effective bearing area of ​​the air spring is obtained from the pressure sensor, in Pa. The instantaneous value of the suspension displacement Determine the air spring's load-bearing capacity, in m². Unit N; effective load-bearing area of ​​the air spring The method of obtaining the data is as follows: during the air spring test bench calibration process, for different instantaneous values ​​of the airbag temperature and different instantaneous values ​​of the air spring pressure, the instantaneous value of the suspension displacement is changed and the corresponding air spring load-bearing capacity is measured. Reverse calculate the effective load-bearing area of ​​the air spring, establish a lookup table relationship between the effective load-bearing area of ​​the air spring and the instantaneous value of the suspension displacement, and make the instantaneous value of the suspension displacement... After inputting the lookup table relationship, the corresponding effective bearing area of ​​the air spring is output; the mechanical workload of the air spring is also output. according to Calculation, where For the first The suspension operating cycle is defined by the time interval between two adjacent identical suspension mid-states. The instantaneous value of the suspension speed is given in m / s; the integral is converted to a measure of the first... Each sampling time within the aforementioned suspension working cycle Sum of the products of the sampling time interval, where Take the values ​​at each sampling time point, in J; Indicates the first Within the first suspension working cycle, the Each sampling time, This indicates the air spring's load-bearing capacity at the sampling time. The instantaneous value of the suspension speed at the sampling time; the mechanical workload of the air spring. Indicates the first The cumulative absolute value of the product of the air spring load-bearing force and the instantaneous value of the suspension speed within each suspension working cycle is used to characterize the degree of mechanical energy exchange between the air spring and the suspension; for the first The suspension operating cycle is described in one of the following ways, to include the first... The most recent consecutive suspension working cycles, including the aforementioned suspension working cycles. The aforementioned suspension work cycles constitute the sliding window, and the suspension work cycle sequence number within the sliding window... for arrive ,in The integer is a positive integer. It is obtained by conducting air spring bench tests, driving an electric all-terrain vehicle under various road surface and load conditions, collecting the mechanical workload of the air spring during multiple suspension work cycles, and then considering multiple candidate integers. Calculate the ratio of the standard deviation to the mean of the mechanical workload of the air spring within the sliding window, and select the candidate integer that minimizes the ratio. Determined as the Verify the The calculation delay shall not exceed the suspension control cycle; the suspension control cycle is determined by the scheduling cycle of the suspension control task in the vehicle controller, and the execution cycle of the suspension control task is read from the vehicle controller as the suspension control cycle; the instantaneous value of the suspension speed is calculated according to the suspension working cycle, and the peak value is taken as the first peak value. The maximum absolute value of the instantaneous suspension speed within each suspension working cycle is taken as the peak suspension speed of the cycle. The peak suspension speeds of each suspension working cycle are summed within the sliding window and then divided by [the summation of the peak suspension speeds within the sliding window]. The average peak value of the suspension speed is obtained. The formula is ,in For the first The peak suspension speed of each suspension work cycle, in m / s; when the number of suspension work cycles within the sliding window is insufficient. The average value of the existing suspension working cycle is used as a substitute; the displacement position corresponding to the geometric midpoint of the suspension design working stroke is taken as the suspension midpoint position. When the suspension displacement crosses from one side of the midpoint position to the other side and returns to the midpoint position, a suspension working cycle is determined by the midpoint position timestamp of two adjacent crosses in the same direction or under the same judgment condition.

[0040] acoustic emission raw signal Bandwidth filtering is performed to obtain the acoustic emission filtered signal. ; Filter the acoustic emission signal The acoustic emission filtered signal is compared with a preset amplitude threshold. An acoustic emission event is formed within a continuous time period exceeding a preset amplitude threshold; the number of events is statistically analyzed. The number of acoustic emission events generated within each suspension working cycle is used to obtain the acoustic emission event count. ; Filtering of acoustic emission signals In the One suspension working cycle By performing square integration within the inner quadratic region, the acoustic emission signal energy is obtained. According to the preset reference mechanical workload and preset reference acoustic emission signal energy Normalization is performed to obtain and ,in, To normalize the mechanical workload of the air spring, Normalized acoustic emission signal energy; acoustic emission response per unit mechanical workload The calculation formula is: The degree of acoustic emission event activity per unit time The calculation formula is: ,in For the first The length of time for each suspension working cycle This is the preset reference frequency.

[0041] It should be explained that the original acoustic emission signal The acoustic emission signal is obtained by the acoustic emission sensor and then filtered by frequency band filtering to obtain the filtered acoustic emission signal. The filtering band of the frequency band filter is determined as follows: the original acoustic emission signals are collected from both a healthy air spring and an air spring with known fatigue damage; the original acoustic emission signals are then subjected to discrete Fourier transform on each segment of the original acoustic emission signals to obtain the power spectral density corresponding to the healthy air spring. Power spectral density corresponding to known fatigue-damaged air springs ,in For frequency; according to Calculate the difference in power spectral density between the two. ,when When it is zero, Replace it with the minimum non-zero power spectral density of the original acoustic emission signal at the same frequency point before recalculating. ;Will The continuous frequency band with a difference greater than the background spectrum fluctuation is determined as the filtering frequency band; the continuous frequency band with a difference greater than the background spectrum fluctuation is determined as the filtering frequency band, and a bandpass filter is used to implement this; the background spectrum fluctuation is determined by the original acoustic emission signal of the healthy air spring in an undamaged state, the original acoustic emission signal of the healthy air spring in an undamaged state is divided into time windows according to the suspension working cycle, and a discrete Fourier transform is performed on each time window to obtain the corresponding power spectral density, and the standard deviation of the power spectral density at the same frequency point in each time window is taken as the background spectrum fluctuation; the acoustic emission filtering signal Compared with a preset amplitude threshold, the preset amplitude threshold is determined according to... Calculation, where The preset amplitude threshold, The mean background noise amplitude of the acoustic emission filtered signal under the condition of a healthy, undamaged air spring. The standard deviation of the background noise amplitude of the acoustic emission filtered signal under the condition of a healthy, undamaged air spring is given. These are weighting coefficients; The method of acquisition is as follows: the acoustic emission filtered signal is collected under the condition of a healthy, undamaged air spring, and the arithmetic mean of the amplitude of each sampling point is used as the... ; The method of acquisition is to collect the acoustic emission filtered signal under the condition of a healthy, undamaged air spring, and use the standard deviation of the amplitude at each sampling point as... ; The acquisition method involves using the acoustic emission filtered signal of a healthy, undamaged air spring as a no-event sample, and the acoustic emission filtered signal of a known fatigue-damaged air spring at the time of the damage event as an event sample, targeting multiple candidate air springs. When the acoustic emission filtered signal is greater than When an event is identified as an acoustic emission event, the proportion of event samples correctly identified as acoustic emission events and no event samples correctly identified as non-acoustic emission events is calculated. The candidate event corresponding to the largest proportion is selected. Determined as ; in the acoustic emission filtered signal An acoustic emission event is formed within a continuous time period exceeding the preset amplitude threshold. A dead time is set. When the time interval between two adjacent continuous time periods exceeding the threshold is less than the dead time, they are merged into one acoustic emission event. The dead time is obtained by marking the actual start and end times of the same damage event and adjacent damage events in the acoustic emission event sequence of known fatigue-damaged air springs. For multiple candidate dead times, the number of times the same damage event is repeatedly counted and the number of times adjacent damage events are mistakenly merged are counted respectively. The candidate dead time corresponding to the minimum sum of the repeated counts and the mistaken merging counts is determined as the dead time. The count of the first... The number of acoustic emission events generated within each suspension working cycle is used to obtain the number of acoustic emission events. ; for the acoustic emission filtered signal In the The aforementioned suspension working cycle The acoustic emission signal energy is obtained by performing a square integral within the interval, as shown in the formula: The integral is converted to a measure of the first element under discrete sampling. The summation of the squared value of the acoustic emission filtered signal at each sampling time within the suspension working cycle and the sampling time interval, with the unit determined by the output unit of the acoustic emission sensor; the preset reference mechanical workload The method for obtaining the data is as follows: under reference load, reference suspension displacement amplitude, and reference suspension speed, the healthy air spring is continuously operated to form the suspension working cycle one by one, according to... Calculate the air spring mechanical workload for each suspension work cycle until the change in the arithmetic mean of the air spring mechanical workload after adding a new suspension work cycle is less than the standard deviation of the noise in the air spring mechanical workload measurement. Take the arithmetic mean of the air spring mechanical workload as... The preset reference acoustic emission signal energy The method of obtaining it is, in conjunction with... Under the same reference load, reference suspension displacement amplitude, and reference suspension speed, the healthy air spring is continuously operated to form the suspension working cycle one by one, and the acoustic emission filtered signal is processed according to... The acoustic emission signal energy is calculated for each suspension duty cycle until the change in the arithmetic mean of the acoustic emission signal energy after adding a new suspension duty cycle is less than the standard deviation of the acoustic emission signal energy measurement noise. The arithmetic mean of the acoustic emission signal energy at this point is then taken as the standard deviation. According to the preset reference mechanical workload and the preset reference acoustic emission signal energy Normalization is performed to obtain and ,in The normalized mechanical workload of the air spring is given. The normalized acoustic emission signal energy; the acoustic emission response per unit mechanical workload. ,when When the amount is less than the correction amount to prevent the denominator from being zero, Replace with the correction amount and then calculate. The correction measurement during the calibration of the healthy air spring The minimum non-zero value; the degree of activity of the acoustic emission event per unit time. ,in For the first The duration of each suspension working cycle is obtained by the difference between the timestamps corresponding to the median states of two adjacent identical suspensions. The preset reference frequency is the reciprocal of the suspension working cycle time of the healthy air spring under reference load, reference suspension displacement amplitude, and reference suspension speed; the acoustic emission response per unit mechanical workload is... Describes the acoustic emission response corresponding to a unit of mechanical workload, wherein the activity level of the acoustic emission event per unit time is... Describes the degree of acoustic emission activity per unit time.

[0042] Get the drive wheel number For the first Each drive wheel, based on a pre-calibrated effective wheel radius. Instantaneous value of wheel angular velocity Calculate the linear velocity of the wheel The formula is: Based on the instantaneous value of vehicle speed Calculate wheel drive slip ratio The formula is: ,in To preset the low-speed protection value; based on the instantaneous value of the motor torque. and instantaneous value of motor angular velocity Calculate the power of the driving machinery ; Calculate the first Average drive mechanical power per suspension working cycle The formula is: A moving average was applied to the acoustic emission response per unit of mechanical workload and the activity level of acoustic emission events per unit time to obtain... and ,in For the first Acoustic emission response per unit mechanical workload of a suspension work cycle. For the first The degree of acoustic emission activity per unit time in each suspension work cycle; calculation of suspension motion. The formula is: ,in This represents the average peak value of the suspension speed. Preset reference suspension speed; calculate the deviation of acoustic emission response per unit mechanical workload. The formula is: ,in The acoustic emission response of a healthy air spring under the same mechanical working conditions is determined by a pre-calibrated reference unit of mechanical workload; the deviation of the acoustic emission event activity level per unit time is calculated. The formula is: ,in The degree of acoustic emission event activity per unit time is pre-calibrated for a healthy air spring under the same mechanical working conditions; the degree of electric drive load is calculated. The formula is: ,in Preset reference driving mechanical power; calculate nonlinear interaction quantities before acoustic emission criticality. The formula is: ,in , , and The weighting coefficients for the nonlinear interaction quantities before the critical acoustic emission threshold.

[0043] It should be explained that the drive wheel number The drive wheel number is read from the vehicle controller based on the drive architecture of the electric all-terrain vehicle, when the vehicle has only one drive wheel. Take the unique number corresponding to the drive wheel. When the vehicle has multiple drive wheels, the drive wheel number is... The wheels are numbered sequentially according to their driving positions: left front drive wheel, right front drive wheel, left rear drive wheel, and right rear drive wheel; the effective radius of the wheels... The method for obtaining the rolling radius is as follows: In a static state, the static rolling radius is determined based on the tire's outer diameter as specified in the tire specifications and the radial deformation of the tire under a reference load. In a dynamic state, the actual distance the vehicle travels during one wheel rotation is measured and divided by the angular change corresponding to one wheel rotation to obtain the dynamic rolling radius. Either the static rolling radius or the dynamic rolling radius is then used as the effective radius of the wheel. The unit is meters (m). Alternatively, under specified tire pressure, vehicle load, and reference road conditions, the vehicle is driven stably at low speed along a straight line. Wheel angular displacement and actual travel distance are collected simultaneously. The ratio of the actual travel distance to the wheel angular displacement is used to determine the dynamic effective radius of the wheel. Repeated measurements are performed for different vehicle loads and tire pressures. The dynamic effective radii obtained under each condition are statistically analyzed to form the effective radius calibration value for the corresponding wheel number j. For the first wheel... Each drive wheel, with the effective radius of the wheel With the instantaneous value of the wheel angular velocity according to Multiply to obtain the linear velocity of the wheel The instantaneous value of the wheel angular velocity The linear velocity of the wheel is obtained from the wheel angular velocity sensor, in rad / s. The unit is m / s; based on the instantaneous value of the vehicle speed. Calculate the wheel drive slip ratio The formula is The instantaneous value of the vehicle speed mentioned above The preset low-speed protection value is obtained from the vehicle controller. The method for obtaining the noise fluctuation range of the instantaneous vehicle speed is as follows: when the vehicle is stationary and the drive motor is not outputting torque, the noise fluctuation range of the instantaneous vehicle speed is collected, and the value that is greater than the upper limit of the noise fluctuation range and less than the minimum normal driving speed of the vehicle is determined as the preset low speed protection value. Alternatively, under conditions where the vehicle is stationary and the drive motor is not outputting torque, instantaneous vehicle speed values ​​can be collected, and the fluctuation range of vehicle speed measurement noise can be statistically analyzed. Simultaneously, the lowest stable driving speed under normal driving conditions can be obtained. Candidate values ​​greater than the upper limit of the vehicle speed measurement noise fluctuation range and less than the lowest stable driving speed under normal driving conditions are selected as candidate values ​​for low-speed protection. The smallest candidate value that can prevent the denominator of the slip ratio calculation from approaching zero under stationary or low-speed conditions and does not change the calculation result of the slip ratio under normal driving conditions is selected as the lowest stable driving speed protection value. ; to ensure that the denominator is not zero at low vehicle speeds and does not change the wheel drive slip ratio during normal driving. The calculation results show that the wheel drive slip ratio It is a dimensionless quantity; based on the instantaneous value of the motor torque. and the instantaneous value of the motor angular velocity Calculate the power of the driving mechanism The instantaneous value of the motor torque and the instantaneous value of the motor angular velocity The instantaneous value of the motor torque is obtained from the drive motor controller. The instantaneous value of the motor's angular velocity is in N·m. The unit is rad / s, and the power of the driving machinery is... Unit W, summation symbol This represents the summation of the absolute values ​​of the products of the drive motor torque and the motor angular velocity for all drive wheels; calculating the... The average drive mechanical power of the suspension in each working cycle ,in For the first The duration of each suspension working cycle, in seconds. For the first The suspension operating cycle, wherein the integral is converted under discrete sampling to the first... The drive mechanical power at each sampling time within the suspension working cycle. Sum of the products of the sampling time interval and the product of the two sampling time intervals, then divide by the product of the two sampling time intervals. The average driving mechanical power The unit is W; acoustic emission response to the unit mechanical workload. and the degree of activity of acoustic emission events per unit time The moving average is calculated using the following formula: and ,in For the first Acoustic emission response per unit mechanical workload of the suspension working cycle. For the first The degree of acoustic emission event activity per unit time in each suspension duty cycle. The moving average, being a positive integer similar to the aforementioned sliding window, is used to reduce the impact of random noise and single obstacle impact on the acoustic emission response during a single suspension duty cycle; the degree of suspension motion is calculated. ,in The average value of the peak suspension speed. The preset reference suspension speed is the speed at which the preset reference suspension speed is set. The method for obtaining the value is as follows: under reference load, reference suspension displacement amplitude, and reference suspension speed, the healthy air spring is continuously operated to form the suspension working cycle one by one. The peak suspension speed of each suspension working cycle is calculated in the aforementioned manner until the change in the arithmetic mean of the peak suspension speed after adding a new suspension working cycle is less than the standard deviation of the peak suspension speed measurement noise. The arithmetic mean of the peak suspension speed at this time is taken as the value. The unit is m / s; calculate the deviation of the acoustic emission response per unit of mechanical work. ,in The acoustic emission response of a healthy air spring under the same mechanical working conditions, pre-calibrated as a reference unit of mechanical workload, is obtained by continuously running the healthy air spring under the same air spring pressure, airbag temperature, suspension displacement range, and peak suspension speed conditions as the current suspension working cycle, forming the suspension working cycle one by one. The acoustic emission response of the unit of mechanical workload for each suspension working cycle is calculated until the change in the arithmetic mean of the acoustic emission response of the unit of mechanical workload after adding a new suspension working cycle is less than the standard deviation of the measurement noise. The arithmetic mean of the acoustic emission response of the unit of mechanical workload is then taken as the reference value. , To prevent corrections where the denominator is zero, the method of obtaining the correction is to take... and The minimum non-zero value during the calibration process of the healthy air spring; calculate the deviation of the activity level of the acoustic emission event per unit time. ,in The reference unit-time acoustic emission event activity level for a healthy air spring, pre-calibrated under the same mechanical working conditions, is obtained by continuously running the healthy air spring under the same air spring pressure, airbag temperature, suspension displacement range, and peak suspension speed conditions as the current suspension working cycle, forming the suspension working cycle one by one. The unit-time acoustic emission event activity level is calculated for each suspension working cycle until the change in the arithmetic mean of the unit-time acoustic emission event activity level after adding a new suspension working cycle is less than the standard deviation of the measured noise. The arithmetic mean of the unit-time acoustic emission event activity level is then taken as the reference value. ; Calculate the electric drive load level ,in The preset reference drive mechanical power is obtained by driving the electric all-terrain vehicle at a reference speed under reference load and reference road conditions, calculating the average drive mechanical power for each suspension work cycle, until the change in the arithmetic mean of the average drive mechanical power after adding a new suspension work cycle is less than the standard deviation of the measurement noise, and then taking the arithmetic mean of the average drive mechanical power as the reference value. Unit W; calculate the nonlinear interaction before the acoustic emission criticality. ,in , , and The weighting coefficients for the nonlinear interaction quantities before the acoustic emission criticality are given. , , and The method of obtaining the data is to collect the deviation of the acoustic emission response per unit mechanical workload of a healthy air spring and a known pre-critical fatigue-damaged air spring under the suspension working cycle. The deviation of the activity level of the acoustic emission event per unit time The degree of suspension movement and the electric drive load level The suspension working cycle corresponding to a healthy air spring is labeled as the first state label, and the suspension working cycle corresponding to an air spring with known pre-critical fatigue damage is labeled as the second state label, using the acoustic emission pre-critical nonlinear interaction quantity. The objective is to minimize the sum of squared errors between the first and second state labels. , , and As the variable to be optimized, gradient descent is used for iterative updates. , , and Until the sum of squared errors no longer decreases, the result obtained at this point... , , and As the weighting coefficient of the nonlinear interaction quantity before the critical acoustic emission threshold; in the formula The nonlinear interaction quantity between the square of the deviation of the acoustic emission response per unit mechanical workload and the pre-critical acoustic emission quantity. Individual contributions, The nonlinear interaction quantity between the squared term representing the deviation of the acoustic emission event activity level per unit time and the pre-critical acoustic emission level. Individual contributions, This represents the interaction between the deviation of the acoustic emission response per unit of mechanical workload and the deviation of the acoustic emission event activity per unit time, and is expressed through the degree of suspension movement. The contribution after normalized modulation This indicates the deviation of the acoustic emission response per unit of mechanical workload from the electric drive load level. The interaction between them and the degree of electric drive load The contribution after normalized modulation This is the hyperbolic tangent function, used to map the sum of the terms within parentheses to a bounded interval.

[0044] Calculate the nonlinear interaction variation between adjacent suspension duty cycles The formula is: ,in For the first The acoustic emission pre-critical nonlinear interaction quantity of each suspension working cycle; constructing the pre-critical change quantity. The formula is: In recent times In each suspension working cycle, the statistics satisfy... Suspension duty cycle ratio The formula is: ,in For indicator functions, Preset threshold for change before criticality; critical approximation index for airbag fatigue damage. The calculation formula is: ,in For preset weighting coefficients; when And from the first A preset number of suspension working cycles are continuously advanced forward by one suspension working cycle. satisfy At that time, it was determined that the fatigue damage inside the load-bearing composite layer of the air spring airbag had entered the pre-critical evolution state. For the first The critical approach index for airbag fatigue damage per suspension working cycle. This is a preset threshold before the critical point.

[0045] It should be explained that the change in the nonlinear interaction quantity according to calculate, For the first The acoustic emission pre-critical nonlinear interaction quantity of each suspension duty cycle. For the first The acoustic emission pre-critical nonlinear interaction quantity of each suspension working cycle; A positive value indicates an increase compared to the previous cycle. A negative value indicates a decrease compared to the previous cycle; the first... If the previous loop does not exist, then Set to zero and delay the determination; the change before the critical point according to Build, Indicates to After performing exponential mapping, subtracting the baseline value amplifies positive increases and compresses negative decreases. Indicates to The stabilized normalization term makes Bounded and avoids zero denominator; in the most recent In the aforementioned suspension working cycle, according to Statistical satisfaction The suspension duty cycle ratio , This is an indicator function; it returns 1 if the condition is true and 0 if the condition is false. The preset threshold for pre-critical change is obtained by calculating the suspension's working cycle while both healthy air springs and air springs with known pre-critical fatigue damage are running continuously. Healthy individuals are labeled as the first state, and those with known critical conditions are labeled as the second state. The search threshold within the given range is selected as the threshold that maximizes the accuracy in distinguishing between the two types of labels. Insufficient loop count within the sliding window The calculation is based on the existing number of cycles; the critical approximation index for airbag fatigue damage is as follows. according to calculate, The preset weighting coefficients are obtained by selecting candidate weights between 0 and 1, and calculating the corresponding cycles of a healthy air spring and a known critical air spring. ,by The objective is to maximize the accuracy in distinguishing between the first and second state labels, and the candidate weights that achieve the highest accuracy are selected as the target weights. ; express according to Weighted, express according to Weighted complements, multiplied together to make Simultaneously reflects the intensity of changes in a single adjacent cycle and the most recent The proportion of time the change exceeds the limit in each cycle; when And from the first A preset number of consecutive cycles forward. satisfy At that time, it is determined that the internal fatigue damage of the air spring airbag bearing composite layer has entered the pre-critical evolution state. For the first A cycle , To preset the pre-critical threshold, the method is to obtain the air springs that are known to have entered the pre-critical evolution state. With healthy air springs Compare the two options and choose the one that maximizes the accuracy of the distinction. Value as The method for obtaining the continuously preset number is as follows: before the known critical point, the air spring is fatigued and damaged. In the sequence, statistics start from the first occurrence. The number of cycles between the actual confirmation of entering the pre-critical evolutionary state is taken as the continuous preset number; in the continuous determination, when the cycle... Not greater than The continuous count is reset to zero and then restarted. It is used only as a predictive index obtained from the detectable acoustic emission physical response and is not defined as the amount of damage to the material itself. , Refer to this for the method of obtaining it; requiring that it not be negative is a standard operating procedure.

[0046] The stiffness mapping function for a healthy target is obtained by calibrating the stiffness using different combinations of instantaneous air spring pressure, airbag temperature, and suspension displacement. Based on the instantaneous value of the air spring pressure Instantaneous airbag temperature and instantaneous value of suspension displacement The current target stiffness of the air spring was obtained by using the calibration relationship of the healthy air spring test bench. The formula is: Based on the critical approximation index of airbag fatigue damage Calculate and predict the effective stiffness of the air spring The formula is: ,in To predict the effective stiffness sensitivity coefficient; to predict stiffness deviation The calculation formula is: .

[0047] It should be explained that the health target stiffness mapping function The method for obtaining the target stiffness is as follows: On an air spring test bench, a healthy air spring is subjected to different combinations of instantaneous air spring pressure, instantaneous airbag temperature, and instantaneous suspension displacement. For each combination, suspension displacement excitation is applied, and the changes in air spring load capacity and suspension displacement are measured. The target stiffness for each combination is calculated based on the ratio of the change in air spring load capacity to the change in suspension displacement. Suspension work cycles are continuously formed for each combination until the change in the arithmetic mean of the target stiffness after adding a new suspension work cycle is less than the standard deviation of the measurement noise of the target stiffness. The arithmetic mean of the target stiffness is taken as the target stiffness corresponding to that combination. The instantaneous air spring pressure, instantaneous airbag temperature, and instantaneous suspension displacement values ​​for each combination are used as inputs, and the corresponding target stiffness is used as the output. A lookup table interpolation method is used to establish a mapping function for the target stiffness. For inputs exceeding the calibration range, a boundary-preserving method is used to output the healthy target stiffness of the nearest calibration point; based on the instantaneous value of the air spring pressure... Instantaneous airbag temperature and instantaneous value of suspension displacement Input the health target stiffness mapping function The current target stiffness of the air spring is obtained using the following formula: The instantaneous values ​​of the air spring pressure are in Pa, the instantaneous values ​​of the airbag temperature are in °C, the instantaneous values ​​of the suspension displacement are in meters, and the current target stiffness of the air spring is... The unit is N / m; based on the critical approximation index for airbag fatigue damage. Calculate and predict the effective stiffness of the air spring ,in To predict the effective stiffness sensitivity coefficient, the method is to measure the actual effective stiffness of a healthy air spring and an air spring with known pre-critical fatigue damage on an air spring test bench, and then compare the actual effective stiffness with... The objective is to minimize the sum of squared errors between the calculated predicted effective stiffness of the air springs, in the candidate... Within the range, a step size search method with successively halved intervals is adopted, based on the healthy target stiffness measured by the air spring test bench. The actual effective stiffness of the air spring with known pre-critical fatigue damage. ,according to Reverse calculation The candidate values, among which The critical approximation index for airbag fatigue damage in the corresponding suspension working cycle of the air spring before known critical fatigue damage is defined as follows: The lower limit of the candidate index is set to zero, and the upper limit is set to the maximum value among all back-calculated candidate values. The difference between the upper and lower limits is used as the initial search interval, with an initial step size half the length of the initial search interval. The sum of squared errors at the midpoint of the interval is calculated, and the result is determined based on the sum of squared errors... The increasing direction retains a half-interval containing the sum of squared small errors. The step size is updated to half the length of the updated interval. This process of halving the interval and comparing errors is repeated until the length of the updated interval is less than... The resolution, the The resolution is calculated by dividing the standard deviation of the noise from the actual effective stiffness measurement by . and The product of these factors is used to obtain the product of the factors that minimize the sum of squared errors within the final interval. As the predicted effective stiffness sensitivity coefficient; in the formula The square of the critical approximation index for airbag fatigue damage is used to reflect the degree of critical approximation. This represents the increase in stiffness reduction ratio as the critical fatigue damage index of the airbag increases, causing the predicted effective stiffness of the air spring to decrease relative to the current healthy target stiffness of the air spring as the degree of fatigue damage critical approach increases; the formula for calculating the predicted stiffness deviation is as follows: ,in The unit N / m represents the difference between the current target healthy stiffness of the air spring and the predicted effective stiffness of the air spring.

[0048] upper limit of target stiffness of air spring The calculation formula is: ,in This represents the upper limit of the initial target stiffness of the air spring. The upper limit of the target stiffness of the air spring is the compression coefficient; the target value of the damper's compression damping is... The calculation formula is: ,in Basic compression damping, This is the gain coefficient for the compression damping stiffness deviation. This is the compression damping velocity correction factor; the slip factor calculation formula is: ,in The preset reference slip ratio is used; the formula for calculating the target value of the shock absorber's rebound damping is: ,in Based on rebound damping, This is the gain coefficient for rebound damping stiffness deviation. This is the rebound damping speed correction coefficient.

[0049] It should be explained that the upper limit of the target stiffness of the air spring is... according to Calculation, where The initial target stiffness upper limit of the air spring is obtained by mapping the healthy target stiffness function during the healthy air spring test bench calibration. The maximum value of the output within the calibrated input range is taken as... Unit: N / m; The shrinkage coefficient, which is the upper limit of the target stiffness of the air spring, is obtained by conducting fatigue tests on air spring benches for candidate air springs. Candidates are selected one by one within the range. The lower limit is 0 and the upper limit is 1, calculated according to the formula. With the constraint that the target stiffness of the rear air spring does not exceed the predicted effective stiffness of the air spring, and with the goal of minimizing the suspension vibration response, candidate elements that minimize the target are selected. As , Dimensionless; The critical approximation index for airbag fatigue damage is dimensionless, and is given in the formula. To achieve the normalization critical approximation degree, as It increases and approaches 1. The contraction is formed by multiplying the normalized critical approximation by the amount of normalization. Follow Increase and decrease; the target value of the damper's compression damping is according to Calculation, where The basic compression damping is obtained by changing the shock absorber compression damping under reference load and reference suspension speed and measuring the root mean square of the vehicle body's vertical acceleration. The compression damping that minimizes the root mean square is taken as the base compression damping. The unit is N·s / m; The gain coefficient for the compression damping stiffness deviation, in units of s, is obtained by selecting from the candidate... Candidates are selected one by one within the range. With the objective of minimizing the root mean square (RMS) of the vertical acceleration of the vehicle body after compensation, candidate vehicles that minimize the RMS are selected. As ; The compression damping velocity correction coefficient is dimensionless and is obtained by selecting from the candidate... Candidates are selected one by one within the range. With the objective of minimizing the error between the shock absorber output damping force and the target damping force at different suspension speeds, candidate damping forces that minimize this error are selected. As ; The predicted stiffness deviation is expressed in N / m. The instantaneous value of the suspension speed is expressed in m / s. The preset reference suspension speed is given in m / s; in the formula... Basic items, This is a stiffness deviation compensation term. As the velocity correction factor, Increase and increase and tend to The slip factor Calculation, where The preset reference slip ratio is obtained by applying different driving slip ratios to the tires of an electric all-terrain vehicle on a tire test bench and measuring the tire longitudinal force. The driving slip ratio corresponding to the peak value of the tire longitudinal force as the driving slip ratio increases is taken as the reference slip ratio. Dimensionless; exist much smaller When the time approaches 1, Much larger When the time approaches zero; the target value of the rebound damping of the damper is based on Calculation, where The basic rebound damping is obtained by changing the shock absorber rebound damping under reference load and reference suspension speed and measuring the root mean square of the vehicle body's vertical acceleration. The rebound damping that minimizes the root mean square is taken as the baseline. The unit is N·s / m; The rebound damping stiffness deviation gain coefficient, in units of s, is obtained by selecting from the candidate... Candidates are selected one by one within the range. With the objective of minimizing the root mean square (RMS) of the vertical acceleration of the vehicle body after compensation, candidate vehicles that minimize the RMS are selected. As ; The rebound damping velocity correction coefficient is dimensionless and is obtained by selecting from the candidate... Candidates are selected one by one within the range. With the objective of minimizing the error between the shock absorber output damping force and the target damping force at different suspension speeds, candidate damping forces that minimize this error are selected. As ; in the formula Basic items, This is a stiffness deviation compensation term. For speed correction factor, The slip constraint factor; according to The upper limit of the target stiffness adjustment range of the air spring is limited to: Depending on whether the suspension is currently in the compression or rebound phase, [the following will be done]: or The target damping output for the current suspension stage is sent to the adjustable damping shock absorber.

[0050] Calculate the current actual vehicle body vibration response The formula is: ,in The instantaneous value of the vehicle's vertical acceleration; the root mean square value of the preset reference vehicle's vertical acceleration. The damping is corrected using a closed-loop method based on the baseline to obtain the final target damping. ,in This is the target damping for the current suspension phase; when the suspension is currently in the compression phase... Target value for compression damping of the shock absorber When the suspension is currently in the rebound phase, The target value for the rebound damping of the shock absorber ; The gain coefficient is corrected for the damping closed loop; when the airbag fatigue damage critically approaches the index. Less than the preset critical threshold At the same time, maintain the normal target stiffness adjustment range of the air spring, and the control range of the compression damping and rebound damping of the shock absorber; when Greater than the preset critical threshold Then, the target stiffness adjustment range of the air spring is limited, and the target values ​​of the shock absorber compression damping and rebound damping are re-determined based on the predicted stiffness deviation. Closed-loop correction is performed using the instantaneous value of the vehicle body's vertical acceleration. Restore to the preset release threshold During the following preset number of suspension work cycles, the normal air spring target stiffness adjustment range and shock absorber compression damping and rebound damping control range are restored; among which... This is the preset release threshold.

[0051] It should be explained that the current actual vehicle body vibration response... according to Calculation, where The instantaneous value of the vertical acceleration of the vehicle body is obtained by the vertical acceleration sensor, and the unit is m / s². For the first The duration of each suspension working cycle, in seconds; For the first The suspension operating cycle is described; the integral is converted into a measure of the first under discrete sampling. The product of the square of the instantaneous value of the vehicle body vertical acceleration at each sampling time within the suspension working cycle and the sampling time interval is summed and then divided by . Take the square root again, and you will get The unit m / s² represents the root mean square energy of the vehicle body's vertical vibration within the current suspension operating cycle; the preset reference root mean square value of the vehicle body's vertical acceleration. The method for obtaining the data is as follows: under healthy air spring conditions, reference load, and reference suspension speed, the vehicle is continuously driven to form the suspension working cycle one by one. The current actual vehicle vibration response of each suspension working cycle is calculated until the change in the arithmetic mean after adding a new suspension working cycle is less than the measurement noise standard deviation of the instantaneous value of the vehicle vertical acceleration. The arithmetic mean of the current actual vehicle vibration response at this point is taken as the data. The final target damping Calculation, where The target damping for the current suspension stage is determined based on the sign of the instantaneous suspension speed and the direction of suspension displacement change when the current suspension is in the compression stage. Take the target value of the compression damping of the vibration damper When it is determined that the current suspension is in the rebound phase, Take the target value of the rebound damping of the shock absorber ; The hyperbolic tangent function is used to... Mapping to a bounded interval Greater than Shishi relatively Increase Less than Shishi relatively Decrease; The damping closed-loop correction gain coefficient is obtained by selecting from the candidate... Candidates are selected one by one within the range. To correct the current actual vehicle body vibration response and The objective is to minimize the sum of squared errors and prevent sustained oscillations in the final target damping. Candidates that minimize this sum of squared errors are selected. As When the airbag fatigue damage critical approach index Less than the preset critical threshold At the same time, maintain the normal target stiffness adjustment range of the air spring, and the control range of the compression damping and rebound damping of the shock absorber; when Greater than Then, the target stiffness adjustment range of the air spring is limited, and the target values ​​of the shock absorber compression damping and rebound damping are re-determined based on the predicted stiffness deviation. Closed-loop correction is performed using the instantaneous value of the vehicle body vertical acceleration. Restore to the preset release threshold During the following, and continuing for a preset number of suspension working cycles, the normal air spring target stiffness adjustment range and the shock absorber compression damping and rebound damping control range are restored; wherein The method of obtaining the index is as follows: during the test process in which the air spring recovers as the damage stops proliferating after entering the pre-critical evolution state of the known pre-critical fatigue damage air spring, the critical approximation index of the airbag fatigue damage is recorded. The value decreases to a level that no longer triggers the pre-critical decision, and this value is taken as... ,make Less than To form hysteresis; the preset quantity is obtained by determining the critical approach index for airbag fatigue damage. Restore to The following steps involve counting the number of suspension working cycles required for the target values ​​of the shock absorber compression damping, the shock absorber rebound damping, and the air spring target stiffness adjustment range to return to stability. This number is then used as the preset number. During the counting process of this preset number, when the suspension working cycles reach a certain threshold... Greater than When the count is reset, the counter will be cleared and the count will restart.

[0052] Example 2: Based on Example 1, a coordinated control system for suspension stiffness and damping of an electric all-terrain vehicle, such as... Figure 2 As shown, it also includes:

[0053] The suspension operation data acquisition module is used to acquire instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed. The time interval between two adjacent identical suspension mid-states is defined as a suspension working cycle.

[0054] The mechanical workload calculation module is used to calculate the air spring bearing capacity based on the instantaneous value of the air spring pressure and the effective bearing area of ​​the air spring. Within one suspension working cycle, the absolute value of the product of the air spring bearing capacity and the instantaneous value of the suspension speed is integrated to obtain the mechanical workload of the air spring. The original acoustic emission signal is processed to obtain the acoustic emission response per unit mechanical workload and the degree of acoustic emission event activity per unit time.

[0055] The acoustic emission critical identification module is used to construct the nonlinear interaction quantity before the acoustic emission criticality based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load. Based on the changing trend of the nonlinear interaction quantity before the acoustic emission criticality of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles, the critical approximation result of airbag fatigue damage is determined.

[0056] The air spring stiffness prediction module is used to predict the effective stiffness and predicted stiffness deviation of the air spring based on the critical approximation results of airbag fatigue damage and the calibration relationship of healthy air spring bench.

[0057] The stiffness-damping coordinated control module is used to limit the target stiffness adjustment range of the air spring based on the predicted stiffness deviation, redetermine the target values ​​of the shock absorber compression damping and rebound damping, and use the instantaneous value of the vehicle body vertical acceleration to perform closed-loop correction on the target values ​​of the shock absorber compression damping and rebound damping.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle, characterized in that, Includes the following steps: S1: Acquire instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed. Define the time interval between two adjacent identical suspension mid-states as a suspension working cycle. S2: Calculate the air spring bearing capacity based on the instantaneous value of the air spring pressure and the effective bearing area of ​​the air spring. Integrate the absolute value of the product of the air spring bearing capacity and the instantaneous value of the suspension speed within one suspension working cycle to obtain the mechanical workload of the air spring. Process the original acoustic emission signal to obtain the acoustic emission response per unit mechanical workload and the degree of acoustic emission event activity per unit time. S3: Construct the nonlinear interaction quantity before the critical acoustic emission based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load. Determine the critical approximation result of airbag fatigue damage based on the changing trend of the nonlinear interaction quantity before the critical acoustic emission of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles. S4: Based on the critical approximation results of airbag fatigue damage and the calibration relationship of healthy air spring test bench, predict the effective stiffness and predicted stiffness deviation of air spring; S5: Based on the predicted stiffness deviation, limit the target stiffness adjustment range of the air spring, redetermine the target values ​​of the shock absorber compression damping and rebound damping, and use the instantaneous value of the vehicle body vertical acceleration to perform closed-loop correction on the target values ​​of the shock absorber compression damping and rebound damping.

2. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The acquisition of instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed, defining the time interval between two adjacent identical suspension neutral states as a suspension working cycle, includes: installing an acoustic emission sensor on the outer surface of the air spring airbag; installing pressure and temperature sensors in the air spring air circuit; installing a suspension displacement sensor in the suspension mechanism; installing a vertical acceleration sensor on the vehicle body; and installing a wheel angular velocity sensor on the wheel. The system uses sensors to acquire instantaneous vehicle speed values ​​from the vehicle controller, instantaneous motor torque values ​​and instantaneous motor angular velocity values ​​from the drive motor controller; the acoustic emission sensor is used to acquire the raw acoustic emission signal, the pressure sensor is used to acquire the instantaneous air spring pressure value, the temperature sensor is used to acquire the instantaneous airbag temperature value, the suspension displacement sensor is used to acquire the instantaneous suspension displacement value, the vertical acceleration sensor is used to acquire the instantaneous vehicle body vertical acceleration value, and the wheel angular velocity sensor is used to acquire the instantaneous wheel angular velocity value; the instantaneous suspension speed value is obtained by time differentiation of the instantaneous suspension displacement value.

3. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The air spring load-bearing capacity is calculated based on the instantaneous value of the air spring pressure and the effective load-bearing area of ​​the air spring. The mechanical workload of the air spring is obtained by integrating the absolute value of the product of the air spring load-bearing capacity and the instantaneous value of the suspension speed within one suspension working cycle. This includes: air spring load-bearing capacity. The calculation formula is: ,in This represents the instantaneous value of the air spring pressure. To be based on the instantaneous value of suspension displacement Determined effective load-bearing area of ​​the air spring; mechanical workload of the air spring. The calculation formula is: ,in For the first One suspension working cycle, For the instantaneous value of the suspension speed; for the first Each suspension work cycle, including the first The most recent continuous suspension work cycle, including the last one. Each suspension work cycle constitutes a sliding window, and the suspension work cycle number within the sliding window... for arrive For the instantaneous values ​​of suspension speed, calculate the peak value according to the suspension working cycle, sum the peak values ​​of suspension speed for each suspension working cycle within the sliding window, and then divide by . The average peak value of the suspension speed was obtained. .

4. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The process of processing the raw acoustic emission signal to obtain the acoustic emission response per unit of mechanical workload and the activity level of acoustic emission events per unit time includes: processing the raw acoustic emission signal... Bandwidth filtering is performed to obtain the acoustic emission filtered signal. ; Filter the acoustic emission signal The acoustic emission filtered signal is compared with a preset amplitude threshold. An acoustic emission event is formed within a continuous time period exceeding a preset amplitude threshold; the number of events is statistically analyzed. The number of acoustic emission events generated within each suspension working cycle is used to obtain the acoustic emission event count. ; Filtering of acoustic emission signals In the One suspension working cycle By performing square integration within the inner quadratic region, the acoustic emission signal energy is obtained. According to the preset reference mechanical workload and preset reference acoustic emission signal energy Normalization is performed to obtain and ,in, To normalize the mechanical workload of the air spring, Normalized acoustic emission signal energy; acoustic emission response per unit mechanical workload The calculation formula is: The degree of acoustic emission event activity per unit time The calculation formula is: ,in For the first The length of time for each suspension working cycle This is the preset reference frequency.

5. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The construction of the pre-critical nonlinear interaction quantity for acoustic emission based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load includes: obtaining the drive wheel number. For the first Each drive wheel, based on a pre-calibrated effective wheel radius. Instantaneous value of wheel angular velocity Calculate the linear velocity of the wheel The formula is: Based on the instantaneous value of vehicle speed Calculate wheel drive slip ratio The formula is: ,in Preset low-speed protection value; based on the instantaneous value of motor torque. and instantaneous value of motor angular velocity Calculate the power of the driving machinery ; Calculate the first Average drive mechanical power per suspension working cycle The formula is: A moving average was applied to the acoustic emission response per unit of mechanical workload and the activity level of acoustic emission events per unit time to obtain... and ,in For the first Acoustic emission response per unit mechanical workload of a suspension work cycle. For the first The degree of acoustic emission activity per unit time in each suspension work cycle; calculation of suspension motion. The formula is: ,in This represents the average peak value of the suspension speed. Preset reference suspension speed; calculate the deviation of acoustic emission response per unit mechanical workload. The formula is: ,in The acoustic emission response of a healthy air spring under the same mechanical working conditions is determined by a pre-calibrated reference unit of mechanical workload; the deviation of the acoustic emission event activity level per unit time is calculated. The formula is: ,in The degree of acoustic emission event activity per unit time is pre-calibrated for a healthy air spring under the same mechanical working conditions; the degree of electric drive load is calculated. The formula is: ,in Preset reference driving mechanical power; calculate nonlinear interaction quantities before acoustic emission criticality. The formula is: ,in , , and The weighting coefficients for the nonlinear interaction quantities before the critical acoustic emission threshold.

6. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The determination of the critical approximation result for airbag fatigue damage based on the trend of changes in the nonlinear interaction quantity before the critical acoustic emission of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles includes: calculating the changes in the nonlinear interaction quantity between adjacent suspension working cycles. The formula is: ,in For the first The acoustic emission pre-critical nonlinear interaction quantity of each suspension working cycle; constructing the pre-critical change quantity. The formula is: In recent times In each suspension working cycle, the statistics satisfy... Suspension duty cycle ratio The formula is: ,in For indicator functions, Preset threshold for change before criticality; critical approximation index for airbag fatigue damage. The calculation formula is: ,in For preset weighting coefficients; when And from the first A preset number of suspension working cycles are continuously advanced forward by one suspension working cycle. satisfy At that time, it was determined that the fatigue damage inside the load-bearing composite layer of the air spring airbag had entered the pre-critical evolution state. For the first The critical approach index for airbag fatigue damage per suspension working cycle. This is a preset threshold before the critical point.

7. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The method for predicting the effective stiffness and predicted stiffness deviation of the air spring based on the critical approximation results of air spring fatigue damage and the calibration relationship of healthy air spring benches includes: obtaining a healthy target stiffness mapping function by performing stiffness calibration on different combinations of instantaneous air spring pressure values, different instantaneous air spring temperature values, and different instantaneous suspension displacement values. Based on the instantaneous value of the air spring pressure Instantaneous airbag temperature and instantaneous value of suspension displacement The current target stiffness of the air spring was obtained by using the calibration relationship of the healthy air spring test bench. The formula is: Based on the critical approximation index of airbag fatigue damage Calculate and predict the effective stiffness of the air spring The formula is: ,in To predict the effective stiffness sensitivity coefficient; to predict stiffness deviation The calculation formula is: .

8. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The process of limiting the target stiffness adjustment range of the air spring based on the predicted stiffness deviation and re-determining the target values ​​of the damper's compression damping and rebound damping includes: the upper limit of the target stiffness of the air spring. The calculation formula is: ,in This represents the upper limit of the initial target stiffness of the air spring. The upper limit of the target stiffness of the air spring is the compression coefficient; the target value of the damper's compression damping is... The calculation formula is: ,in Basic compression damping, This is the gain coefficient for the compression damping stiffness deviation. This is the compression damping velocity correction factor; the slip factor calculation formula is: ,in The preset reference slip ratio is used; the formula for calculating the target value of the shock absorber's rebound damping is: ,in Based on rebound damping, This is the gain coefficient for rebound damping stiffness deviation. This is the rebound damping speed correction coefficient.

9. The method for coordinated control of suspension stiffness and damping of an electric all-terrain vehicle according to claim 1, characterized in that, The closed-loop correction of the target values ​​for shock absorber compression damping and rebound damping using the instantaneous value of the vehicle body's vertical acceleration includes: calculating the current actual vehicle body vibration response. The formula is: ,in The instantaneous value of the vehicle's vertical acceleration; the root mean square value of the preset reference vehicle's vertical acceleration. The damping is corrected using a closed-loop method based on the baseline to obtain the final target damping. ,in This is the target damping for the current suspension phase; when the suspension is currently in the compression phase... Target value for compression damping of the shock absorber When the suspension is currently in the rebound phase, The target value for the rebound damping of the shock absorber ; The gain coefficient is corrected for the damping closed loop; when the airbag fatigue damage critically approaches the index. Less than the preset critical threshold At the same time, maintain the normal target stiffness adjustment range of the air spring, and the control range of the compression damping and rebound damping of the shock absorber; when Greater than the preset critical threshold Then, the target stiffness adjustment range of the air spring is limited, and the target values ​​of the shock absorber compression damping and rebound damping are re-determined based on the predicted stiffness deviation. Closed-loop correction is performed using the instantaneous value of the vehicle body's vertical acceleration. Restore to the preset release threshold During the following preset number of suspension work cycles, the normal air spring target stiffness adjustment range and shock absorber compression damping and rebound damping control range are restored; among which... This is the preset release threshold.

10. A suspension stiffness and damping coordinated control system for an electric all-terrain vehicle, used to implement the suspension stiffness and damping coordinated control method for an electric all-terrain vehicle as described in any one of claims 1-9, characterized in that, Also includes: The suspension operation data acquisition module is used to acquire instantaneous values ​​of air spring pressure, airbag temperature, suspension displacement, vehicle vertical acceleration, acoustic emission, wheel angular velocity, motor torque, motor angular velocity, and vehicle speed. The time interval between two adjacent identical suspension mid-states is defined as a suspension working cycle. The mechanical workload calculation module is used to calculate the air spring bearing capacity based on the instantaneous value of the air spring pressure and the effective bearing area of ​​the air spring. Within one suspension working cycle, the absolute value of the product of the air spring bearing capacity and the instantaneous value of the suspension speed is integrated to obtain the mechanical workload of the air spring. The original acoustic emission signal is processed to obtain the acoustic emission response per unit mechanical workload and the degree of acoustic emission event activity per unit time. The acoustic emission critical identification module is used to construct the nonlinear interaction quantity before the acoustic emission criticality based on the acoustic emission response per unit mechanical workload, the activity level of acoustic emission events per unit time, the degree of suspension movement, and the degree of electric drive load. Based on the changing trend of the nonlinear interaction quantity before the acoustic emission criticality of adjacent suspension working cycles and the statistical proportion of continuous suspension working cycles, the critical approximation result of airbag fatigue damage is determined. The air spring stiffness prediction module is used to predict the effective stiffness and predicted stiffness deviation of the air spring based on the critical approximation results of airbag fatigue damage and the calibration relationship of healthy air spring bench. The stiffness and damping coordinated control module is used to limit the target stiffness adjustment range of the air spring based on the predicted stiffness deviation, redetermine the target values ​​of the shock absorber compression damping and rebound damping, and use the instantaneous value of the vehicle body vertical acceleration to perform closed-loop correction on the target values ​​of the shock absorber compression damping and rebound damping.

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