EA021468B1 - Method of preflyght monitoring of technical condition of aviation engineering - Google Patents

Abstract

The invention relates to information-measuring systems, in particular, to methods of diagnosis of preflight condition of aviation engineering. The essence of the invention consists in collecting measuring information, its processing by methods of spectral and statistic analysis, setting identification parameters and their evaluation. As parameters informative criterium of static analysis are used: assessment of dispersion interference Dε, assessment of cross-correlation functions between the interference and useful signal Rε(μ), assessment of cross-correlation functions between the useful signals R(μ), received from different sensors, correlation coefficient rand spectral estimation of a real signal a, b. In case of the deviation of at least one parameter assessment of the static analysis from the reference value starting period of defect nucleation is set. The deviation of a, bassessments from the reference values means transition the object to emergency state. The effectiveness of the proposed method provides simple calculation and reliability of assessments of informative criterium. The method of monitoring aviation engineering can be used for monitoring technical condition for any object subjected to different dynamic loads.

Description

The invention relates to information-measuring systems, and in particular to methods for diagnosing the pre-flight technical condition of aviation equipment in order to prevent their accident rate during operation.

In aviation technology, as in any other, during operation, the probability of destruction of structural elements is very high. In most cases, the integrity violation occurs under the influence of operational factors such as load level, environmental impact, etc. The effectiveness of the process of technical operation of aircraft largely depends on the reliability of monitoring the technical condition of aircraft and their engines, the reliability of which, in turn, is associated with the elemental base and the entire control system. However, despite the increased reliability of the element base, and the entire system as a whole, the number of accidents with catastrophic consequences due to the fault of control and management systems decreased slightly.

A known method of technical diagnostics of an aircraft engine and airframe, using the so-called binary diagnostic system (1). This system includes a list of diagnostic techniques from visual to probabilistic-statistical using specially developed algorithms for the precautionary state of a controlled object. As a solution, this method gives two diagnostic signs associated with the corresponding condition: yes or no. Moreover, the decision on pre-failure condition does not mean at all specifically refusal. This may be a warning condition or need to be repaired. But, most importantly, this method allows you to determine only the transition from one state to another, i.e. seen as instant. This diagnostic leap indicates the inefficiency of this method. Because he either with a large margin issues a decision for repair, or with no less delay - for a malfunction. But both of them are an undesirable fact, because if in the first case it is only material damage, then in the second it is catastrophic consequences.

The closest in technical essence is a method for diagnosing the technical condition of gas turbine engines of an airplane (2) by the methods of spectral analysis of vibration signals. This method is characterized by the presence of a large number of vibration sensors (from 40 to 100 pcs), which are located on all vulnerable elements of the object. The method collects measurement information received from vibration sensors located on a large number of heterogeneous elements of the object, identifies the signals and determines the values of their parameters for comparison with pre-formed reference parameters and their values and makes a decision. Information processing is carried out by spectral analysis methods, the parameters of which are the frequency or amplitude of the vibration, the value of which is obtained in the form of estimates a _p , b _p - coefficients of the Fourier series of the real signal. The vibration level depends on many factors: the principle of operation of the element, the method of application of the vibration sensors and the level of dynamic forces and moments acting in it, their distance from the vibration source, the location and method of attachment of the vibration sensors, the characteristics of the vibration sensor itself, etc., including from the time and location of the aircraft and from the environment. The method allows to determine for all elements of the object sequentially and / or parallelly varying vibration in certain frequency ranges and make the appropriate decision. However, the disadvantage of this method is that monitoring is carried out only in relation to the engine and does not affect other objects of the aircraft. The main disadvantage of this method is the inability to ensure the reliability of monitoring the onset of the defect initiation due to the fact that all signals coming from vibration sensors, both for creating a reference base and for identifying the current signal, are thoroughly cleaned from the accompanying signals, which are the total interference ε ( ίΔΐ). This leads to a distortion of information, since this method allows you to diagnose only pronounced malfunctions and in no way reacts to microdamage, which in flight mode and an unfortunate combination of factors can lead to a plane crash.

The objective of the invention is to develop an effective and reliable method for pre-flight diagnostics of the technical condition of aviation equipment in order to determine the onset (latent period) of a defect through a new technology for analyzing noisy signals β (ίΔΙ).

The essence of the invention lies in the fact that the method of pre-flight monitoring of the technical condition of aircraft, includes the collection of measurement information, its processing by spectral and statistical analysis, the development of identification parameters and estimates of their values. As parameters, informative signs of statistical analysis are used: estimates of the interference variance Ό _ε , estimates of the cross-correlation functions between the interference and the useful signal Κ _χε (μ); estimates of the correlation functions between the useful signals _{полез χχ} (μ); obtained from various sensors, correlation coefficient τ _Χε and spectral estimates of the real signal a _p , b _p . When deviating from the reference values of at least one of the estimates of the parameters of the statistical analysis, the beginning of the defect nucleation period is established. The deviation of the values of the estimates an, bn, spectral analysis from the reference means the transition of the object to an emergency state.

A comparative analysis of the proposed solutions with the prototype showed that in the claimed invention, in contrast to the known, apply a new method of signal analysis based on the use of

- 1 021468 interference signal as a carrier of additional diagnostic information. In this case, as a signal identification parameters, a complex of informative features is used, including estimates of the interference variance Ό _ε , estimates of the mutual correlation functions between the interference and the useful signal Κ _χε (μ); estimates of the cross-correlation functions between the useful signals Κ _χχ (μ) obtained from various sensors, the correlation coefficient Γ _Χε . A comparative analysis of the claimed invention with other known solutions showed that the solution (3) is known, which uses the same complex of informative features as in the claimed invention. However, the object of the known solution is a compressor unit in a static state relative to the environment. Aviation facilities are not only in a state of dynamics, but also in constantly changing environmental conditions, which affects the reliability of estimates of informative features and, thereby, greatly complicates the monitoring process. Therefore, as assessments for comparison, we use not the zero value of the assessments of informative features, as in the well-known solution (3), but a certain standard of the range of assessments developed during training under the normal state of the aircraft under various operating conditions and in accordance with the technical requirements of operation. Thus, the introduction of new features gives reason to argue that the proposed solution meets the requirements of the criterion of novelty. It is known (4, 5) that the normal state of any object, including aircraft, is characterized by noisy technological parameters obtained from the corresponding sensors. Moreover, during the time T ₀ - the period of the normal state, the spectral estimates a _p , b _p correspond to the reference coefficients of the normal state of the object, and for the technological parameters of statistical analysis:

equality holds

Ou He

those. all parameter estimates are approximately zero.

Where

- the law of distribution of the signal § (ΐΔΐ);

Ό _ε , Ό _Χ , Ό ₆ - estimates of the variances of the interference, useful and total signals, respectively;

Κ _ΧΧ (μ), Κ ₆₆ (μ) - estimates of the correlation functions of the useful signal Χ (ίΔΐ) and the total signal § (ίΔί);

πι _ε . t _x , t _d - mathematical expectation of interference, useful and total signals;

Κ _Χε (μ = 0), Γ _Χε is the _cross -correlation function and the correlation coefficient between the useful signal Χ (ίΔΐ) and the noise ε (ΐΔΐ). It is also known (5, 6) that estimates of the spectral analysis a _n , b _n , allow one to determine only the transition of one state to another, namely the transition of the time period T ₀ to the time period T ₂ . However, it is known (5,6) that in the indicated period from T ₀ to T ₂ , i.e. during the period Τι, there is a continuous change in the estimates Κ _ΧΧ (μ), Κ ₆₆ (μ) of the signal characteristics § (ίΔΐ) = Χ (ίΔΐ) + ε (ίΔΐ) obtained at the outputs of the corresponding sensors. Since in this time interval Τι, in addition to the useful signal information Χ (ΐΔΐ), the interference ε (ίΔΐ) also becomes a carrier of diagnostic information. At the same time, in traditional technologies, this specificity of interference ε (εΔΐ) is neglected, focusing only on the estimates a _p , b _p . This is the reason for the adoption by the information systems of inadequate decisions to the situations that have arisen in the initial stage of the transition of aircraft, in particular, the aircraft from normal to emergency. This fact is explained by the fact that spectral estimates are reliable only in cases when the amount of interference varies within limited limits, which is not typical for aviation technology. It has been found that when the process of formation (nucleation) of the defect and a period of latent T _s transition to the emergency state begins, then the above equation is violated, statistical evaluation signal § (ίΔΐ) are determined with an error and all estimation parameters for a period of time T continuously vary . In this period of time T _b, due to the mutual influence of the totality of multifactorial conditions, there is a change in the estimates of informative signs: Ό _ε , Κ ₆₆ (μ), Κ _06ν (μ) and Γ _{Χ ε} , not just from zero, but within a certain range. Therefore, the excess of the values of the variance estimates, auto- and cross-correlation functions Κ ₆₆ (μ) and Κ _06ν (μ) for a certain time shift μ '(μ = μ'Δΐ) and the correlation coefficient between the useful signal and the noise _{ΐ Χε of the} limits of the values of the corresponding reference range , can be considered indicators of the beginning of the transition from a time period T ₀ to a latent time period T _Таким Thus, the listed features are significant, and their combination creates a new technical effect, which allows us to conclude that the claimed invention criteria, the technical level and, therefore, the claimed solution can be recognized by the invention.

The method is as follows.

To conduct pre-flight monitoring of the aircraft, vibration sensors are located in its vulnerable places. The analysis of signals from installed sensors is carried out both in static mode and in conditions determined by the requirements of safe operation. Given that the latent period of time T transition to the emergency state T _{2 is} reflected in the technological parameters of the signals:

£, (M> £ ₂ Ο ^δ Ο, ··, Ζ, Μ, ·, ^ ('Additional estimates are determined by the formulas:

From the obtained estimates, the corresponding sets of informative features are formed:

Similarly, according to estimates of signal interference variances calculated by the formula * 77Σк0 ^Δί > ⁺ ε (' ^Δ ') £ (('+ 2) Δί) -2 £ (ίΔί) ^ ((ΐ + Ι) Δί)] Α, .ι form the sets ν _{ε of the} corresponding informative features

Then according to the formulas = 0) ”= 0) - = 2) - ^ (a = 3))] - _{и and} (a = o)] and r. ^e Va = 0) form the sets νχε from estimates of the mutual correlation functions and the correlation coefficient between the useful signal and the noise in the form =

In addition to the estimates of statistical analysis, the coefficients of the Fourier series of the real signal a _n , b _{n are} determined by the formulas

B „= Τ 5 (ί'Δχ) ϊίη» ω (/ Δ /)

Τ ', ₌ ι and form the sets' b "

where a _p , b _p are the coefficients of the Fourier series of the real signal.

Reference sets of estimates of informative features in the form of a group of the indicated sets: ν ₆ , ν _ε , ν _{Χ ε} and are generated for all necessary and expected situations of aircraft operation.

In the period of time T ₀ , when the object is in a normal state, all elements of the sets of informative features ν ₆ , ν _ε , ν _{Χ ε} and will be in the reference range. At the moment of defect initiation, the deviation of any element of the sets ν ₆ , ν _ε , ν _{Χ ε} from the reference range by the system will be perceived as the beginning of the transition of the monitoring object from the normal time period T ₀ to the latent period of the emergency time period T _b. the number of the column and row of the location of the element of an informative feature that differs from the reference range can be determined, i.e. identify the location and nature of the malfunction. Deviation of any of the elements of the set \ ν, _ιΙ:, from the reference one will mean an emergency condition of the unit of the object of equipment, i.e. period T ₂ . The combination of three informative sets with spectral analysis is reliable and can significantly increase the reliability of monitoring results.

The effectiveness of the proposed method lies in the fact that the calculation of the estimates of each of the listed indicators is quite simple, and the results are reliable. In addition, the joint use of these indicators and estimates of a _p , b _p obtained by spectral analysis of measurement information increases the reliability of pre-flight monitoring of aircraft, and the monitoring method of aircraft can be used to monitor the technical condition for any object subjected to various dynamic loads .

Literature

Claims (1)

CLAIM A method for pre-flight monitoring of the technical condition of aviation equipment, including the collection of measurement information from vibration sensors located on vulnerable elements of aircraft, its processing and generation of identification parameters, which are used as spectral estimates of the real signal a ^x p, b ^x p for comparison with similar ones, in advance generated reference estimates, and if the current estimates deviate from the reference ones, a defect is established, characterized in that the method further includes statistics esky analysis measurement information, as identification parameters use a dispersion interference estimate Ό _ε, the estimated correlation coefficient Γ _χε and cross-correlation functions between interference and the useful signal Κ _χε (μ); estimates of the cross-correlation functions between the K ₆₆ (c) signals received from various sensors, and if at least one of the parameter estimates deviates from the reference range, the beginning of the defect initiation period is established.