Multi-stage bolt tightening feature construction method based on monitoring data

Abstract

The invention discloses a multi-stage bolt tightening feature construction method based on monitoring data. The feature construction method comprises the following four steps: carrying out multi-stage division on a bolt tightening process; setting starting conditions of a bolt tightening stage; setting end conditions of a bolt tightening stage; and extracting the characteristics of the bolt tightening process. Time sequence data of angles and torques of a bolt multi-stage tightening process are used as a data source, an inspected stage of a tightening curve is accurately positioned through stage division, starting condition selection and ending condition selection, and characteristics of tightening data are extracted through calculation of process characteristics. The problem that the correlation between the input features of the algorithm and the classification labels is low when fault detection is carried out in the bolt multi-stage tightening process is solved.

Description

Technical Field

[0001] The present invention relates to a method for constructing characteristics of the bolt tightening process, especially a method for constructing multi-stage bolt tightening characteristics based on monitoring data. It belongs to the field of data-driven fault detection. Background Art

[0002] Multi-stage bolt tightening refers to a bolt tightening method in which multiple tightening stages are sequentially executed to achieve final pre-tightening. When developing a fault detection algorithm for the multi-stage bolt tightening process, it is necessary to construct characteristics as the input of the algorithm. The main difficulties in characteristic construction are as follows: the pre-tightening of a bolt includes multiple stages and the tightening methods in each stage are different; process characteristics such as elastic rebound, creep, and nonlinearity lead to a decrease in characteristic accuracy; there are various types of errors in the multi-stage bolt tightening process. Therefore, it is valuable to study a method for constructing the state characteristics of multi-stage bolt tightening based on process data. Summary of the Invention

[0003] The present invention provides a method for constructing multi-stage bolt tightening characteristics based on monitoring data. The monitoring data refers to the time series data of the angle and torque collected during the tightening process, that is, the change of the angle over time and the change of the torque over time. The multi-stage bolt tightening refers to a bolt tightening method in which multiple tightening stages are sequentially executed to achieve final pre-tightening. The characteristics are used to characterize the abnormal conditions and abnormal categories of bolt tightening. The characteristics constructed by the method of the present invention can be used as the input characteristics of the fault detection algorithm for the multi-stage bolt tightening process. The method of the present invention is used to solve the problem of low correlation between the input characteristics of the algorithm and the classification labels when performing fault detection on the multi-stage bolt tightening process.

[0004] Constructing the characteristics of multi-stage bolt tightening based on monitoring data is divided into the following four steps: 1. Multi-stage division of the bolt tightening process. 2. Setting the start condition of the bolt tightening stage. 3. Setting the end condition of the bolt tightening stage. 4. Extracting the bolt tightening process characteristics.

[0005] 1. Multi-stage division module of the bolt tightening process

[0006] The multi-stage division module of the bolt tightening process is used to realize the standardized stage division of the tightening data and select a stage to enter the next operation. The method of the present invention proposes a set of stage division operators, which includes 8 stage division operators. Select a stage division operator from the set of stage division operators and execute it. When a stage division operator is executed, the corresponding part of the tightening data is intercepted as the stage to be inspected.

[0007] The set of stage operators includes 8 stage division operators, and their explanations are as follows:

[0008] 1) Initial meshing stage operator: Intercept the part of the data where the torque is zero and the angle decreases as the inspected stage.

[0009] 2) Screwing-in stage operator: Intercept the part of the data where the torque is zero and the angle increases as the inspected stage.

[0010] 3) Pre-tightening stage operator: Intercept the part of the data starting from where the torque is non-zero to the torque maximum as the inspected stage.

[0011] 4) Pre-tightening target stage operator: Intercept the part of the data where the torque increases and the angle increases as the inspected stage.

[0012] 5) Reverse stage operator: Intercept the part of the data where the torque is first negative and then zero and the angle continuously decreases as the inspected stage.

[0013] 6) Waiting stage operator: Intercept the part of the data where the angle remains unchanged as the inspected stage.

[0014] 7) Yield stage operator: Intercept the part of the data where the angle increases, the torque is non-zero and remains unchanged as the inspected stage.

[0015] 8) Stopping stage operator: Intercept the part of the data starting from the torque maximum point to the end of the data as the inspected stage.

[0016] 2. Bolt tightening stage start condition setting module

[0017] The bolt tightening stage start condition setting module is used to accurately locate the start position of the inspected stage. The method of the present invention proposes a set of start condition operators, which includes 4 start condition operators. Select one start condition operator from the set of start condition operators and execute it. When a start condition operator is executed, the start point is found within the inspected stage, and the part of the inspected stage after the start point is intercepted as the new inspected stage.

[0018] The set of start condition operators includes 4 start condition operators, and their explanations are as follows:

[0019] 1) Starting point operator: Set the data point with the minimum time within the inspected stage as the start point. Intercept the part of the inspected stage after the start point as the new inspected stage.

[0020] 2) Maximum angle operator: Use the data point corresponding to the maximum angle of the previous tightening stage of the inspected stage as the start point. Intercept the part of the inspected stage after the start point as the new inspected stage.

[0021] 3) Fit point operator: The fit point is defined as the data point corresponding to the torque slope reaching 80% of the elastic deformation slope. The fit point is set as the starting point. The part of the inspected stage after the starting point is intercepted as the new inspected stage.

[0022] 4) Maximum torque operator: The data point corresponding to the maximum torque of the previous tightening stage of the inspected stage is taken as the starting point. The part of the inspected stage after the starting point is intercepted as the new inspected stage.

[0023] 3. Bolt tightening phase end condition setting module

[0024] The bolt tightening phase end condition setting module is used to realize the precise positioning of the end position of the inspected phase. The method of the present invention proposes an end condition operator set, which includes 4 end condition operators. An end condition operator is selected from the end condition operator set and executed. When an end condition operator is executed, the end point is found in the inspected phase, and the part of the inspected phase before the end point is intercepted as a new inspected phase.

[0025] The end condition operator set contains 4 end condition operators, which are explained as follows:

[0026] 1) Yield point operator: The yield point is defined as the first data point where the torque slope is less than 50% of the maximum torque slope of this stage. The yield point in the inspected stage is set as the end point. The part of the inspected stage before the end point is intercepted as the new inspected stage.

[0027] 2) Peak torque operator: Set the data point with the maximum torque in the inspected stage as the end point. Cut the part of the inspected stage before the end point as the new inspected stage.

[0028] 3) Peak angle operator: Set the data point with the largest angle in the inspected stage as the end point. Cut the part of the inspected stage before the end point as the new inspected stage.

[0029] 4) End of stage operator: Set the data point with the largest time in the stage to be checked as the end point. Cut the part of the stage to be checked before the end point as the new stage to be checked.

[0030] 4. Bolt tightening process feature extraction module

[0031] The bolt tightening process feature extraction module is used to extract and output process features for the inspected stage. The method of the present invention proposes a process feature operator set, which includes 14 process feature operators. A process feature operator is selected from the process feature operator set and executed. When a process feature operator is executed, the feature value of the inspected stage is calculated and output.

[0032] The set of process feature operators contains 14 process feature operators, and their explanations are as follows:

[0033] 1) Maximum torque operator: Calculate the maximum torque within the inspected stage in the torque-angle relationship.

[0034] Output the maximum torque.

[0035] 2) Minimum torque operator: Calculate the minimum torque within the inspected stage in the torque-angle relationship.

[0036] Output the minimum torque.

[0037] 3) Torque difference operator: Calculate the difference between the maximum and minimum torques within the inspected stage in the torque-angle relationship. Output the difference.

[0038] 4) Average torque operator: Calculate the average torque within the inspected stage in the torque-angle relationship. Output the average torque.

[0039] 5) Time operator: Calculate the tightening duration within the inspected stage in the torque-time relationship. Output the time.

[0040] 6) Angular displacement operator: Calculate the angular change within the inspected stage in the torque-angle relationship, denoted as angular displacement. Output the angular displacement.

[0041] 7) Positive area operator: Calculate the area enclosed by the curve above the X-axis within the inspected stage in the torque-angle relationship. Output the area.

[0042] 8) Negative area operator: Calculate the area enclosed by the curve below the X-axis within the inspected stage in the torque-angle relationship. Output the area.

[0043] 9) Slope operator: Fit the curve of the inspected stage to a straight line using the least squares method in the torque-angle relationship. Calculate the slope of the straight line. Output the slope of the straight line.

[0044] 10) X-intercept operator: Fit the curve of the inspected stage to a straight line using the least squares method in the torque-angle relationship. Calculate the X-intercept of the straight line with respect to the X-axis based on the starting point of the inspected stage. Output the X-intercept.

[0045] 11) Yield operator: The yield point is defined as the first data point where the torque slope is less than 50% of the maximum torque slope of this stage. In the torque-angle relationship, check whether a yield point appears within the inspected stage. If a yield point appears, output 1; if no yield point appears, output 0.

[0046] 12) Continuity operator: In the torque-time relationship, if the torque of a data point is lower than the maximum torque value of the data point on its left, the difference between the two is called the "drop value". Calculate all the drop values within the inspected stage. Output the maximum value among all the drop values.

[0047] 13) High-frequency vibration operator: In the torque-time relationship, calculate the number of maximum points within the inspected stage. Output the number of maximum points.

[0048] 14) Low-frequency vibration operator: First, perform sliding window mean filtering on the time series data of the torque. Then, in the torque-time relationship, calculate the number of maximum points within the inspected stage. Output the number of maximum points.

[0049] A method for constructing multi-stage bolt tightening characteristics based on monitoring data proposed by the present invention realizes the construction of characteristics by successively performing multi-stage division of the bolt tightening process, setting the start condition of the tightening stage, setting the end condition of the tightening stage module, and extracting the tightening process characteristics. For any multi-stage tightening data containing n tightening stages, n stage options, 4 start condition options, 4 end condition options, and 14 process characteristic options can be provided, and a total of n×4×4×14 = 224n characteristics can be constructed. The constructed characteristics are used as input characteristics for the fault detection algorithm of the multi-stage bolt tightening process, and solve the problem of low correlation between the input characteristics of the algorithm and the classification labels when performing fault detection on the multi-stage bolt tightening process. Brief Description of the Drawings

[0050] The present invention will be further described below in conjunction with the drawings and embodiments.

[0051] Figure 1 It is a schematic diagram of the overall flow of the method of the present invention

[0052] Figure 2 It is a schematic diagram of the stage division operator of the method of the present invention

[0053] Figure 3 It is a schematic diagram of the start condition operator of the method of the present invention

[0054] Figure 4 It is a schematic diagram of the definition of the fitting point of the method of the present invention

[0055] Figure 5 It is a schematic diagram of the end condition operator of the method of the present invention

[0056] Figure 6 It is a schematic diagram of the definition of the yield point of the method of the present invention

[0057] Figure 7 It is a schematic diagram of the process characteristic operator of the method of the present invention Detailed Embodiment

[0058] Based on the monitoring data, the characteristics of multi-stage bolt tightening are constructed, which are divided into the following four steps: 1. Multi-stage division of the bolt tightening process. 2. Setting the start condition of the bolt tightening stage. 3. Setting the end condition of the bolt tightening stage. 4. Extracting the process characteristics of bolt tightening. The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments:

[0059] Step 1. Multi-stage division module of the bolt tightening process

[0060] As Figure 1 shown, the multi-stage division module of the bolt tightening process is used to realize the standardized stage division of the tightening data and select a stage to enter the next operation. The method of the present invention proposes a set of stage division operators, which includes 8 stage division operators. Select a stage division operator from the set of stage division operators and execute it. When a stage division operator is executed, the corresponding part of the tightening data is intercepted as the stage to be inspected.

[0061] As Figure 2 shown, the set of stage operators includes 8 stage division operators, and their explanations are as follows:

[0062] 1) Initial meshing stage operator: Intercept the part where the torque is zero and the angle decreases in the data as the stage to be inspected.

[0063] 2) Screwing-in stage operator: Intercept the part where the torque is zero and the angle increases in the data as the stage to be inspected.

[0064] 3) Pre-tightening stage operator: Intercept the part from where the torque is not zero to the maximum torque in the data as the stage to be inspected.

[0065] 4) Pre-tightening target stage operator: Intercept the part where the torque increases and the angle increases in the data as the stage to be inspected.

[0066] 5) Reverse stage operator: Intercept the part where the torque is first negative and then zero and the angle continuously decreases in the data as the stage to be inspected.

[0067] 6) Waiting stage operator: Intercept the part where the angle remains unchanged in the data as the stage to be inspected.

[0068] 7) Yield stage operator: Intercept the part where the angle increases, the torque is not zero and remains unchanged in the data as the stage to be inspected.

[0069] 8) Stop stage operator: Intercept the part from the maximum torque point to the end of the data in the data as the stage to be inspected.

[0070] Step 2. Start condition setting module of the bolt tightening stage

[0071] AsFigure 1 As shown in Figure 1 , the bolt tightening stage start condition setting module is used to accurately locate the start position of the inspection stage. The method of the present invention proposes a set of start condition operators, which includes 4 start condition operators. Select one start condition operator from the set of start condition operators and execute it. When a start condition operator is executed, it will find the start point within the inspection stage and intercept the part of the inspection stage after the start point as the new inspection stage.

[0072] As Figure 3 shown, the set of start condition operators includes 4 start condition operators, and their explanations are as follows:

[0073] 1) Starting point operator: Set the data point with the minimum time within the inspection stage as the start point. Intercept the part of the inspection stage after the start point as the new inspection stage.

[0074] 2) Maximum angle operator: Take the data point corresponding to the maximum angle of the previous tightening stage of the inspection stage as the start point. Intercept the part of the inspection stage after the start point as the new inspection stage.

[0075] 3) Fitting point operator: As Figure 4 shown, the fitting point is defined as the data point corresponding to the torque slope reaching 80% of the elastic deformation slope. Set the fitting point as the start point. Intercept the part of the inspection stage after the start point as the new inspection stage.

[0076] 4) Maximum torque operator: Take the data point corresponding to the maximum torque of the previous tightening stage of the inspection stage as the start point. Intercept the part of the inspection stage after the start point as the new inspection stage.

[0077] Step 3. Setting the end condition of the bolt tightening stage

[0078] As Figure 1 shown, the bolt tightening stage end condition setting module is used to accurately locate the end position of the inspection stage. The method of the present invention proposes a set of end condition operators, which includes 4 end condition operators. Select one end condition operator from the set of end condition operators and execute it. When an end condition operator is executed, it will find the end point within the inspection stage and intercept the part of the inspection stage before the end point as the new inspection stage.

[0079] As Figure 5 shown, the set of end condition operators includes 4 end condition operators, and their explanations are as follows:

[0080] 1) Yield point operator: As Figure 6As shown, the yield point is defined as the first data point where the torque slope is less than 50% of the maximum torque slope in this stage. The yield point within the stage to be inspected is set as the end point.

[0081] The part of the stage to be inspected before the end point is intercepted as the new stage to be inspected.

[0082] 2) Peak torque operator: The data point with the maximum torque within the stage to be inspected is set as the end point. The part of the stage to be inspected before the end point is intercepted as the new stage to be inspected.

[0083] 3) Peak angle operator: The data point with the maximum angle within the stage to be inspected is set as the end point. The part of the stage to be inspected before the end point is intercepted as the new stage to be inspected.

[0084] 4) End-of-stage operator: The data point with the maximum time within the stage to be inspected is set as the end point. The part of the stage to be inspected before the end point is intercepted as the new stage to be inspected.

[0085] Step 4. Extraction of bolt tightening process characteristics

[0086] As Figure 1 shown, the bolt tightening process characteristic extraction module is used to extract process characteristics for the stage to be inspected and output them. The method of the present invention proposes a set of process characteristic operators, which includes 14 process characteristic operators. Select one process characteristic operator from the set of process characteristic operators and execute it. When a process characteristic operator is executed, the characteristic value of the stage to be inspected is calculated and output.

[0087] As Figure 7 shown, the set of process characteristic operators includes 14 process characteristic operators, and their explanations are as follows:

[0088] 1) Torque maximum operator: Calculate the maximum torque within the stage to be inspected in the torque-angle relationship.

[0089] Output the maximum torque.

[0090] 2) Torque minimum operator: Calculate the minimum torque within the stage to be inspected in the torque-angle relationship.

[0091] Output the minimum torque.

[0092] 3) Torque difference operator: Calculate the difference between the maximum torque and the minimum torque within the stage to be inspected in the torque-angle relationship. Output the difference.

[0093] 4) Average torque operator: Calculate the average torque within the stage to be inspected in the torque-angle relationship. Output the average torque.

[0094] 5) Time operator: Calculate the tightening duration of the inspected phase in the torque-time relationship. Output the time.

[0095] 6) Angular displacement operator: Calculate the angular change amount of the inspected phase in the torque-angle relationship, denoted as angular displacement. Output the angular displacement.

[0096] 7) Positive area operator: In the torque-angle relationship, calculate the area enclosed by the curve and the upper part of the X-axis within the inspected phase. Output the area.

[0097] 8) Negative area operator: In the torque-angle relationship, calculate the area enclosed by the curve and the lower part of the X-axis within the inspected phase. Output the area.

[0098] 9) Slope operator: In the torque-angle relationship, fit the curve of the inspected phase to a straight line using the least squares method. Calculate the slope of the straight line. Output the slope of the straight line.

[0099] 10) X-intercept operator: In the torque-angle relationship, fit the curve of the inspected phase to a straight line using the least squares method. Calculate the X-intercept of the straight line with respect to the X-axis based on the starting point of the inspected phase. Output the X-intercept.

[0100] 11) Yield operator: The yield point is defined as the first data point where the torque slope is less than 50% of the maximum torque slope of this phase. In the torque-angle relationship, check whether a yield point appears within the inspected phase. If a yield point appears, output 1; if not, output 0.

[0101] 12) Continuity operator: In the torque-time relationship, if the torque of a data point is lower than the maximum torque value of its left data point, the difference between them is called the "drop value". Calculate all the drop values within the inspected phase. Output the maximum value among all the drop values.

[0102] 13) High-frequency vibration operator: In the torque-time relationship, calculate the number of maximum points within the inspected phase. Output the number of maximum points.

[0103] 14) Low-frequency vibration operator: First, perform sliding window mean filtering on the time series data of torque. Then, in the torque-time relationship, calculate the number of maximum points within the inspected phase. Output the number of maximum points.

[0104] By successively performing multi-stage division of the bolt tightening process, setting the start condition of the tightening phase, setting the end condition of the tightening phase, and extracting the tightening process characteristics, the construction of features is realized. For any multi-stage tightening data containing n tightening phases, n stage options, 4 start condition options, 4 end condition options, and 14 process feature options can be provided, and a total of n×4×4×14 = 224n features can be constructed.

Claims

1. A method for constructing multi-stage bolt tightening features based on monitoring data, characterized in that: The feature construction method is divided into the following steps: Step 1: multi-stage division of the bolt tightening process; Step 2: setting the start conditions of the bolt tightening stage; Step 3: setting the end conditions of the bolt tightening stage; Step 4: extracting the bolt tightening process features; Step 1: The bolt tightening process is divided into multiple stages; A stage division operator set includes 8 stage division operators; a stage division operator is selected from the stage division operator set and executed; when a stage division operator is executed, a corresponding part of the tightening data is intercepted as the checked stage; Step 2: Setting the starting conditions for the bolt tightening phase; A start condition operator set, which includes 4 start condition operators; a start condition operator is selected from the start condition operator set and executed; when a start condition operator is executed, a start point is found in the checked phase, and the part of the checked phase after the start point is intercepted as a new checked phase; Step 3: Setting the end conditions of the bolt tightening phase; The end condition operator set includes 4 end condition operators; an end condition operator is selected from the end condition operator set and executed; when an end condition operator is executed, the end point is found in the checked phase, and the part of the checked phase before the end point is intercepted as the new checked phase; Step 4: Bolt tightening process feature extraction module The process feature operator set includes 14 process feature operators; a process feature operator is selected from the process feature operator set and executed; when a process feature operator is executed, the feature value of the inspected stage is calculated and output.

2. A method for constructing multi-stage bolt tightening features based on monitoring data according to claim 1, characterized in that: In step 1, the stage operator set contains 8 stage partition operators, which are explained as follows: 1) Initial meshing stage operator: The part of the data where the torque is zero and the angle decreases is intercepted as the stage to be checked; 2) Screw-in stage operator: the part of the data where the torque is zero and the angle increases is intercepted as the stage to be examined; 3) Preload stage operator: The part of the data starting from the point where the torque is not zero and ending at the point where the torque is maximum is taken as the stage to be checked; 4) Preload target phase operator: intercept the part of the data where the torque increases and the angle increases as the phase to be checked; 5) Reversal phase operator: intercept the part of the data where the torque is first negative and then zero, and the angle continues to decrease. As the stage under examination; 6) Waiting phase operator: intercepts the part of the data where the angle remains unchanged as the checked phase; 7) Yield stage operator: intercepts the part of the data where the angle increases and the torque is not zero and remains unchanged. As the stage under examination; 8) Stop phase operator: The part of the data starting from the maximum torque point and ending at the end of the data is taken as the checked phase.

3. The method for constructing multi-stage bolt tightening features based on monitoring data according to claim 1, characterized in that: In step 2, the start condition operator set includes 4 start condition operators, which are explained as follows: 1) Starting point operator: set the data point with the smallest time in the checked stage as the starting point; intercept the part of the checked stage after the starting point as the new checked stage; 2) Maximum angle operator: the data point corresponding to the maximum angle of the tightening stage before the inspected stage is taken as the starting point; the part of the inspected stage after the starting point is intercepted as the new inspected stage; 3) Fit point operator: The fit point is defined as the data point corresponding to the torque slope reaching 80% of the elastic deformation slope; the fit point is set as the starting point; the part of the inspected stage after the starting point is intercepted, As a new stage to be examined; 4) Maximum torque operator: the data point corresponding to the maximum torque of the previous tightening stage of the checked stage is taken as the starting point; The part of the inspected phase after the starting point is intercepted as the new inspected phase.

4. The method for constructing multi-stage bolt tightening features based on monitoring data according to claim 1, characterized in that: In step 3, the end condition operator set contains 4 end condition operators, which are explained as follows: 1) Yield point operator: The yield point is defined as the first data point where the torque slope is less than 50% of the maximum torque slope in this stage; the yield point in the checked stage is set as the end point; The part of the inspected phase before the end point is intercepted as a new inspected phase; 2) Peak torque operator: the data point with the maximum torque in the checked stage is set as the end point; The part of the inspected phase before the end point is intercepted as a new inspected phase; 3) Peak angle operator: set the data point with the largest angle in the inspected stage as the end point; intercept the part of the inspected stage before the end point as the new inspected stage; 4) End of stage operator: the data point with the largest time in the checked stage is set as the end point; the part of the checked stage before the end point is intercepted as the new checked stage.

5. The method for constructing multi-stage bolt tightening features based on monitoring data according to claim 1, characterized in that: In step 4, the process feature operator set includes 14 process feature operators, which are explained as follows: 1) Torque maximum operator: calculates the maximum value of the torque in the checked phase in the torque-angle relationship; Maximum output torque; 2) Torque minimum operator: calculates the minimum value of the torque within the checked phase in the torque-angle relationship; Minimum output torque; 3) Torque difference operator: calculates the difference between the maximum and minimum torque values ​​in the checked phase in the torque-angle relationship; Output the difference; 4) Average torque operator: calculates the average torque in the checked phase in the torque-angle relationship; outputs the average torque; 5) Time operator: calculates the duration of tightening in the checked phase in the torque-time relationship; Output the time; 6) Angular displacement operator: Calculate the angle change in the inspected stage in the torque-angle relationship and record it as angular displacement; Output the angular displacement; 7) Positive area operator: In the torque-angle relationship, calculate the area enclosed by the curve in the checked phase and above the X-axis; output the area; 8) Negative area operator: In the torque-angle relationship, calculate the area enclosed by the curve under the X-axis in the checked phase; output the area; 9) Slope operator: In the torque-angle relationship, the curve of the checked stage is fitted into a straight line using the least square method; the slope of the straight line is calculated; and the slope of the straight line is output; 10) Intercept operator: In the torque-angle relationship, the curve of the inspected stage is fitted into a straight line using the least square method; the intercept of the straight line to the X-axis is calculated based on the starting point of the inspected stage; the intercept is output; 11) Yield operator: The yield point is defined as the first data point where the torque slope is less than 50% of the maximum torque slope in this stage; in the torque-angle relationship, find out whether the yield point appears in the checked stage; if the yield point appears, output 1, if the yield point does not appear, output 0; 12) Continuity operator: In the torque-time relationship, if the torque of a data point is lower than the maximum torque value of the data point on its left, the difference between the two is called the "drop value"; calculate all the drop values ​​in the checked stage; output the maximum value of all the drop values; 13) High frequency vibration operator: In the torque-time relationship, the number of maximum points in the checked phase is calculated; Output the number of maximum points; 14) Low-frequency vibration operator: First, perform sliding window mean filtering on the time series data of torque; then, calculate the number of maximum points in the checked stage in the torque-time relationship; and output the number of maximum points.

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