CN104819841A - Built-in-coding-information-based single sensing flexible angle-domain averaging method - Google Patents

Abstract

The utility model relates to a built-in-coding-information-based single sensing flexible angle-domain averaging method. An encoder is used for reading an angular position signal of a testing shaft in mechanical equipment; transient motion information is obtained by using a polynomial fitting method to obtain a third-order differential Jitter signal and a first-order differential rotation speed signal; fluctuation quantities of an angle-domain uniformly-spaced sampling signal and a rotation signal are calculated of the Jitter signal are calculated, a rotation speed fluctuation quantity threshold value is set to determine whether a signal is a stable one, angle-domain resampling is carried out on a non-stable signal exceeding a threshold value, and otherwise, the signal is treated as the stable one and the original j(t) signal serves as a uniform-angle-interval sampling signal; and a chirp-Z-conversion-based flexible angle domain average method is used for determining whether a fault occurs at the mechanical equipment. Therefore, the number of experiment devices is controlled to the great extent; the data acquisition procedures are simplified; the test cost is reduced; automation of fault feature extraction and diagnosis monitoring can be carried out conveniently; the time is saved; and the efficiency is high.

Description

Patrilineal line of descent with only one son in each generation based on built-in coded message feels flexible angle domain averaging method

Technical field

The present invention relates to mechanical fault diagnosis technical field, the patrilineal line of descent with only one son in each generation particularly based on built-in coded message feels flexible angle domain averaging method.

Background technology

The vibration analysis of present stage mechanical fault diagnosis one of effective way the most, in some occasions, vibration-measuring sensor is difficult to install due to environment and operating mode restriction.Numerically-controlled machine sputters a large amount of metal fragments and liquid coolant in the course of the work, can cause damage to vibration-measuring sensor.And for the equipment such as mechanical arm, robot, the athletic posture of its complexity brings difficulty to the installation of vibration-measuring sensor and wiring.In addition, Large Machining Center under arms in require totally enclosed working environment, cause vibration-measuring sensor cannot install at all.Therefore, when vibration information cannot obtain, building new diagnostic message source becomes present stage mechanical fault diagnosis already and needs the problem of solution badly.Along with plant equipment robotization, intelligentized development trend, scrambler obtains extensive configuration as built-in sensing unit on mechanized equipment, position for motion control is fed back, there is measuring accuracy high, fast response time, measurement range is wide, functional reliability good, non-cpntact measurement and be convenient to control advantage.Built-in coded message is the digital quantity signal that the physical quantity such as angular displacement, spin angular position, angular velocity of mechanical rotation being tested on axle changes into, and it can be used as a kind of new diagnostic message source to have broad application prospects in the fault diagnosis of plant equipment and health monitoring.

But the primary output signal of scrambler is a kind of multi-components coupled signal of complexity, it not only comprises the transient rotative speed impact that initial failure causes, and comprises the rated speed fluctuation because load change, gear time-varying rigidity cause simultaneously.And the amplitude of the latter is often more powerful, bring difficulty to the extraction of fault features.Time-domain average technique is a kind of traditional technology for mechanical fault diagnosis, periodic component interested in signal can be extracted, improve signal to noise ratio (S/N ratio), but under it is only applicable to determine speed conditions, and in fact, many important equipments are its running speed non-stationary often under different job requirements or condition.Compare with steady operating mode, the mechanical equipment vibration signal under variable speed becomes particularly complicated, considerably increases the extraction difficulty of fault signature.2013, French scholar Leclere etc. proposed angle domain average technology, for the internal combustion engine under variable speed and Gear Fault Diagnosis.But angle domain average method still depends on the cooperation of key signal, this needs extra sensor installation and increases testing cost and difficulty, and its average algorithm keeps away the adverse effect of unavoidable truncation error to Signal-to-Noise, realize only adopting single-sensor to carry out testing the angle domain averaging method simultaneously truncation error being avoided again to disturb significant.

Summary of the invention

In order to overcome the shortcoming of above-mentioned prior art, the object of the present invention is to provide the patrilineal line of descent with only one son in each generation based on built-in coded message to feel flexible angle domain averaging method, realizing plant equipment and all can carry out fault signature extraction and diagnostic monitoring under steady and variable rotate speed.

For achieving the above object, the technical scheme that the present invention program takes is:

Patrilineal line of descent with only one son in each generation based on built-in coded message feels flexible angle domain averaging method, comprises the following steps:

Step one: utilize scrambler number to adopt card and read built-in encoder signal in plant equipment, high frequency sampling and pre-service are carried out to signal, obtains the angle position signal testing axle, be designated as x (t);

Step 2: adopt polynomial fitting method to obtain the transient motion information of plant equipment, carries out Jitter signal that fitting of a polynomial and third order difference obtain and is designated as j (t) and first order difference obtains tach signal v (t) by x (t);

Step 3: angle domain equal interval sampling sequences y (n) calculating Jitter signal j (t), first calculate the fluctuation of speed amount of tach signal v (t), fluctuation of speed amount is defined as the standard deviation of tach signal divided by mean speed, be 0.5% determine whether stationary signal by setting threshold value, the signal exceeding threshold range is non-stationary signal, need to carry out angle domain resampling to Jitter signal j (t), otherwise as stationary signal process, former j (t) signal i.e. conduct angularly interval sampling signal;

Step 4: adopt based on Chirp-Z (Chirp-Z Transform, CZT) the flexible angle domain averaging method converted, CZT by arranging comb filter in frequency spectrum, carried out retaining by order interested and avoid truncation error, the frequency sampling value obtaining desired output order is obtained by following formula:

$\mathrm{CTZ}\left(y\left(n\right)\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}y\left(n\right)\·{\left({\mathrm{AW}}^{-k}\right)}^{-n}$

In formula, y (n) for angle domain equal interval sampling sequence, N be the length of sequence, A is the polar value of starting sample point, and W is the frequency interval between sampled point, and k is corresponding order,

Then each frequency domain sample value is arranged in vector array according to the form of discrete fourier, changes the angle domain average result namely accurately obtaining and expect order further by inverse discrete Fourier transform, thus determine the fault whether equipment exists.

The present invention, compared to prior art, has following beneficial effect:

A) angle position signal that the present invention can be recorded by scrambler high precision obtains the torsional vibration signals reflecting mechanical health situation, i.e. Jitter signal, Jitter is a kind of useful signal that may be used for mechanical incipient fault detection, and truly can reflect motion and the dynamic characteristic of system.

B) namely scrambler self is a kind of high-precision key phase device, can carry out angle domain resampling under non-stationary operating mode to Jitter signal, eliminates the impact of rotation speed change, is applicable to large fluctuation of speed operating mode.

C) the present invention is on the basis of conventional Time-domain averaging method, the creative flexible angle domain averaging method proposed based on Chirp-Z conversion, order interested, by arranging comb filter in frequency spectrum, can carry out retaining and avoid truncation error by CZT efficiently and accurately, improves signal to noise ratio (S/N ratio).

D) the present invention only utilizes the built-in single encoder information of plant equipment, failure message under the accurate extraction equipment working condition of energy, controlling experimental facilities quantity, simplify data acquisition program, reduce testing expense to a great extent, be conducive to the robotization realizing fault signature extraction and diagnostic monitoring, save time, efficiency is higher.

Accompanying drawing explanation

Fig. 1 is embodiment test platform structure schematic diagram.

Fig. 2 is embodiment planetary gear tooth root crack fault.

Fig. 3 is the inventive method process flow diagram.

Fig. 4 is that the epicyclic gearbox intercepted in example plays parking ticket encoder information.

Fig. 5 carries out to encoder information the Jitter signal that third order difference obtains in example.

To be embodiment carry out to encoder information the velocity information that first order difference obtains to Fig. 6.

Fig. 7 is that in embodiment epicyclic gearbox even running process, planetary gear adopts the result of the inventive method.

Fig. 8 is that embodiment epicyclic gearbox rises in docking process, and planetary gear adopts the result of the inventive method.

Fig. 9 is in embodiment epicyclic gearbox even running process, the result that planetary gear adopts conventional Time-domain average.

Figure 10 is that embodiment epicyclic gearbox rises in docking process, the result that planetary gear adopts conventional Time-domain average.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.

Below will be described for certain epicyclic gearbox planetary gear fault detect testing table, this testing table is by drive motor, shaft coupling, scrambler, magnetic powder brake, the composition such as bearing and epicyclic gearbox, as shown in Figure 1, wherein epicyclic gearbox is interior by ring gear 1, sun gear 2, and three uniform planetary gears 3 form, planet carrier is connected with output shaft, two scramblers are arranged on epicyclic gearbox input shaft and output shaft place, whole device is driven by motor, moment of torsion is delivered to the magnetic powder brake of output terminal from input shaft along epicyclic gearbox, magnetic powder brake completes loading procedure.

Design parameter is as follows: 1) drive motor rated power: 1.2kW, rated speed: 40Hz; 2) epicyclic gearbox ratio of gear: 5.1:1, ring gear 1 number of teeth: 82, modulus: 1, planetary gear 3 number of teeth: 31, modulus: 1, sun gear 2 number of teeth: 20, modulus: 1; 3) planetary gear fault type is tooth root crackle, as shown in Figure 2; 4) the moment of torsion 0.06N*m under magnetic powder brake rated power.

Utilize single code device signal to planetary gear diagnosing malfunction in epicyclic gearbox, application the present invention to experimental data carry out analysiss also and conventional Time-domain averaging method contrast.

As shown in Figure 3, the patrilineal line of descent with only one son in each generation based on built-in coded message feels flexible angle domain averaging method, comprises the following steps:

Step one: utilize scrambler number to adopt card and read built-in encoder signal in plant equipment, high frequency sampling and pre-service are carried out to signal, obtain the angle position signal testing axle, for obtaining a complete parking data, need when usage data to remove initial noise section, intercept 6-10s in whole segment signal and be total to the data of 4s, as shown in Figure 4, be designated as x1;

Step 2: adopt polynomial fitting method to obtain the transient motion information of plant equipment, carries out Jitter signal that fitting of a polynomial and third order difference obtain and is designated as j (t) and first order difference obtains tach signal v1, respectively as shown in Figure 5 and Figure 6 by x1;

Step 3: angle domain equal interval sampling sequences y (n) calculating Jitter signal j (t), first calculate the fluctuation of speed amount of tach signal v1, fluctuation of speed amount is defined as the standard deviation of tach signal divided by mean speed, be 0.5% determine whether stationary signal by setting threshold value, the signal exceeding threshold range is non-stationary signal, for epicyclic gearbox plays stop sign in this example, the standard deviation that tach signal according to Fig. 6 calculates tach signal is 108.8883, average velocity is 253.1542, and then to calculate fluctuation of speed amount be 43.01%, be greater than 0.5%, institute thinks non-stationary signal, need to carry out angle domain resampling to Jitter signal j (t), contrast signal is set to stationary signal in addition, namely using former j (t) signal as angularly interval sampling signal,

Step 4: for obtaining Weak fault information in code device signal, improve signal to noise ratio (S/N ratio), adopt the flexible angle domain averaging method based on Chirp-Z conversion, CZT by arranging comb filter in frequency spectrum, efficiently and accurately order interested carried out retaining and avoid truncation error, in this planet Fault Diagnosis of Gear Case example, by meshing frequency, (number of teeth due to planetary gear is 31 teeth, therefore its meshing frequency is 31 rank) left and right 5 order of side frequency retains, the frequency sampling value obtaining desired output order is obtained by following formula

$\mathrm{CTZ}\left(y\left(n\right)\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}y\left(n\right)\·{\left({\mathrm{AW}}^{-k}\right)}^{-n}$

In formula, y (n) is angle domain equal interval sampling sequence, and N is the intercepting data length of 4 seconds, A deducts starting sample order corresponding to 5 (i.e. 26 rank) for engagement order, W is sampling interval is unit 1 order, and k is corresponding order value is 26,27,28 ... 36

Then each frequency domain sample value is arranged in vector array according to the form of discrete fourier, the angle domain average result that accurately can obtain and expect order is changed further by inverse discrete Fourier transform, as shown in Figure 7 and Figure 8, Fig. 7 is in epicyclic gearbox even running process, planetary gear by flexible angle domain average result when undulate quantity threshold value being set to 0.5%, Fig. 8 is that epicyclic gearbox is rising in docking process, planetary gear by flexible synchronized averaging result when undulate quantity threshold value being set to 0.5%, and Fig. 9 and Figure 10 is the result adopting conventional Time-domain averaging method to obtain, Fig. 9 is in epicyclic gearbox even running process, single code device signal is carried out to the diagnostic result of time domain average, Figure 10 is epicyclic gearbox rising in docking process, single code device signal is carried out to the diagnostic result of time domain average.

By under two kinds of situations, these two kinds of methods contrast, obviously can find out that method proposed by the invention can not only show effect more better than conventional Time-domain averaging method under steady operating mode, and the planetary gear tooth root crack fault that epicyclic gearbox can be diagnosed out on average can not to diagnose out at a shutdown phase conventional Time-domain.It can also be seen that from example, method of the present invention can also artificially adjust the undulate quantity threshold value of designated analysis variable, in conjunction with actual conditions, changes its size within the specific limits, has certain redundance.For improve operation efficiency when identifying fault in various degree.

Claims (1)

1. the patrilineal line of descent with only one son in each generation based on built-in coded message feels flexible angle domain averaging method, it is characterized in that, comprises the following steps:

Step one: utilize scrambler number to adopt card and read built-in encoder signal in plant equipment, high frequency sampling and pre-service are carried out to signal, obtains the angle position signal testing axle, be designated as x (t);

Step 2: adopt polynomial fitting method to obtain the transient motion information of plant equipment, carries out Jitter signal that fitting of a polynomial and third order difference obtain and is designated as j (t) and first order difference obtains tach signal v (t) by x (t);

Step 3: angle domain equal interval sampling sequences y (n) calculating Jitter signal j (t), first calculate the fluctuation of speed amount of tach signal v (t), fluctuation of speed amount is defined as the standard deviation of tach signal divided by mean speed, be 0.5% determine whether stationary signal by setting threshold value, the signal exceeding threshold range is non-stationary signal, need to carry out angle domain resampling to Jitter signal j (t), otherwise as stationary signal process, former j (t) signal i.e. conduct angularly interval sampling signal;

Step 4: adopt the flexible angle domain averaging method based on Chirp-Z conversion, order interested, by arranging comb filter in frequency spectrum, carries out retaining and avoids truncation error by CZT, and the frequency sampling value obtaining desired output order is obtained by following formula:

$\mathrm{CTZ}\left(y\left(n\right)\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}y\left(n\right)\·{\left({\mathrm{AW}}^{-k}\right)}^{-n}$

In formula, y (n) for angle domain equal interval sampling sequence, N be the length of sequence, A is the polar value of starting sample point, and W is the frequency interval between sampled point, and k is corresponding order,

Then each frequency domain sample value is arranged in vector array according to the form of discrete fourier, changes the angle domain average result that accurately can obtain and expect order further by inverse discrete Fourier transform, thus determine the fault whether plant equipment exists.