Lifting speed resolving method based on front and back phase filtering

Abstract

The invention provides a lifting speed resolving method based on front and back phase filtering, which comprises the following steps: analyzing static pressure in flight data, obtaining a first coefficient vector and a second coefficient vector of a filter, generating a forward expansion post-pressure sequence according to the first coefficient vector, and generating a backward expansion post-pressure sequence according to the second coefficient vector; forward filtering is carried out on the original pressure sequence, the pressure sequence after forward expansion and the pressure sequence after backward expansion, and a pressure signal after forward filtering is generated; performing mirror image flipping on the pressure signal after forward filtering according to a time axis, and performing backward filtering on the flipped pressure signal through a backward filtering difference equation to generate a final pressure signal; and calculating the atmospheric rising and falling speed, and calculating the final rising and falling speed through the atmospheric rising and falling speed. Through the atmospheric rising and falling speed resolving method based on forward and backward filtering, the stability of output data is ensured while the real-time responsiveness of atmospheric rising and falling speed data is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lifting speed calculation, and in particular to a lifting speed calculation method based on front and back phase filtering. Background Art

[0002] The atmospheric data system plays an important role in the flight of an aircraft. It is crucial to the successful completion of the aircraft's mission and has a significant impact on the flight quality, navigation and safety of the aircraft. Therefore, in practical applications, the accuracy and real-time responsiveness of the atmospheric data system are required to be high. The vertical velocity solution in the atmospheric data system mainly depends on the static pressure. At present, in order to achieve the stability of the vertical velocity solution in the atmospheric data, the commonly used method is to add different levels and depths of digital filtering to the process of collecting pressure and solving the vertical velocity to achieve the purpose. The introduction of these digital filters will affect the dynamic real-time responsiveness of the solved vertical velocity data. Often, real-time and stability cannot be met at the same time, and the vertical velocity requirements can only be compromised according to different aircraft types, resulting in a phenomenon of losing one thing while gaining the other. For this reason, it is necessary to improve the atmospheric vertical velocity solution algorithm. While improving the real-time responsiveness, it is also necessary to consider the requirements of its stability. Summary of the invention

[0003] In view of this, the embodiments of this specification provide a method for calculating lift velocity based on forward and backward phase filtering, so as to achieve the purpose of improving the real-time responsiveness of atmospheric lift velocity calculation while also meeting the stability requirements.

[0004] The embodiments of this specification provide the following technical solutions:

[0005] A lifting speed calculation method based on front and back phase filtering, comprising:

[0006] Analyze the static pressure in the flight data, obtain the first coefficient vector and the second coefficient vector of the filter, forward-extend the original pressure sequence according to the first coefficient vector to generate a forward-extended pressure sequence, and backward-extend the original pressure sequence according to the second coefficient vector to generate a backward-extended pressure sequence;

[0007] Forward filtering is performed on the original pressure sequence, the pressure sequence after forward expansion and the pressure sequence after backward expansion through a forward filtering difference equation to generate a pressure signal after forward filtering;

[0008] The pressure signal after forward filtering is mirror-flipped along the time axis to generate a flipped pressure signal, and the flipped pressure signal is backward-filtered by a backward-filtering difference equation to generate a final pressure signal;

[0009] The atmospheric lifting velocity is resolved for the final pressure signal to obtain the atmospheric lifting velocity, and the final lifting velocity is obtained through the atmospheric lifting velocity calculation.

[0010] Further, the original pressure sequence is forward extended according to the first coefficient vector to generate a forward extended pressure sequence, and the original pressure sequence is backward extended according to the second coefficient vector to generate a backward extended pressure sequence, including:

[0011] The first data of the original pressure sequence and the second data to the M+1th data of the original pressure sequence are linearly extended to generate a forward extended pressure sequence; wherein M is the length of the forward extension and M is equal to the length of the first coefficient vector;

[0012] The nth data of the original pressure sequence is linearly expanded with the n-1th data to the n+Nth data of the original pressure sequence to generate a backward-expanded pressure sequence; wherein N is the length of the backward expansion and N is equal to the length of the second coefficient vector, and n is the length of the original pressure sequence.

[0013] Furthermore, the atmospheric lifting velocity is solved for the final pressure signal to obtain the atmospheric lifting velocity, including:

[0014] The atmospheric lifting speed is resolved for the final pressure signal, and the pressure change rate within a fixed time Δt in the pressure buffer is calculated;

[0015] According to the value of vertical temperature gradient β, the inverse value of atmospheric pressure gradient is calculated;

[0016] Using the lifting velocity formula, the atmospheric lifting velocity is calculated by the inverse of the atmospheric pressure gradient.

[0017] Furthermore, according to the value of the vertical temperature gradient β, the inverse value of the atmospheric pressure gradient is calculated, including:

[0018] When the vertical temperature gradient β = 0, the inverse value of the atmospheric pressure gradient Among them, P s is the atmospheric static pressure, T b is the atmospheric temperature at the lower boundary of the corresponding layer, g n is the standard acceleration of free fall, R is the special gas constant;

[0019] When the vertical temperature gradient β≠0, the inverse value of the atmospheric pressure gradient Among them, P b is the atmospheric pressure at the lower boundary of the corresponding layer.

[0020] Furthermore, the lifting velocity formula is used to calculate the atmospheric lifting velocity through the inverse of the atmospheric pressure gradient, including:

[0021] The velocity of the atmosphere Among them, Δt is a fixed time period, ΔH is the change in pressure altitude within the Δt time period, is the inverse value of the atmospheric pressure gradient, is the pressure change rate within a fixed time Δt.

[0022] Further, the fixed time period Δt=pressure buffer length*pressure sampling time / 1000.

[0023] A method for calculating vertical speed based on forward and backward phase filtering is used to analyze static pressure in flight data and obtain a first coefficient vector and a second coefficient vector of a filter, comprising:

[0024] Analyze the static pressure in the flight data to determine the technical parameters of the filter;

[0025] The technical parameters of the filter are input into a filter design tool to obtain a first coefficient vector and a second coefficient vector of the filter.

[0026] Furthermore, the technical parameters of the filter include the passband cutoff frequency ωc, the stopband cutoff frequency ωs, the maximum attenuation allowed in the passband αc, and the minimum attenuation that the stopband should reach αs.

[0027] Furthermore, the final pressure signal is consistent in time with the pressure signal after forward filtering.

[0028] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification include at least:

[0029] After applying the lifting speed calculation method of the front and back phase filtering of the embodiment of the present invention to the lifting speed calculation method, the lifting speed delay is shortened and the data stability is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a flow chart of a lifting speed calculation method based on front and rear phase filtering according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] The present invention provides an atmospheric lift velocity solution method based on forward and backward filtering, in which forward and backward filtering is introduced in the process of solving the atmospheric lift velocity, firstly, forward filtering is used to remove high-frequency noise or unnecessary frequency components in the input pressure signal, secondly, the filtered pressure signal is mirror-inverted according to the time axis, and finally, the phase delay introduced by the forward filtering is removed by using backward filtering, so that the output pressure signal is completely consistent with the original signal in time, and the filtering effect of zero phase delay is achieved while smoothing the pressure signal. The atmospheric lift velocity is solved by using the pressure data after the forward and backward filtering, and finally the stability of the output data can be guaranteed as much as possible while improving the real-time responsiveness of the atmospheric lift velocity data.

[0035] The core of the atmospheric lifting speed algorithm based on forward and backward filtering is to smooth the pressure signal by introducing forward and backward filtering into the input raw pressure data. The filtered pressure signal is completely consistent with the original input pressure signal in time, achieving the effect of zero phase delay in the time series. The use of forward and backward filtering involves two important processes: the difference equation used by forward and backward filtering and the design of filter coefficients.

[0036] First, a suitable filter is selected according to the characteristics of the pressure signal, and then the corresponding filter coefficient is obtained. For example, by analyzing the static pressure in the flight data, the technical indicators (technical parameters) of the elliptical filter can be selected. In one embodiment, the technical parameters are the passband cutoff frequency ωc is 1 Hz, the stopband cutoff frequency ωs is 2 Hz, the maximum attenuation αc allowed by the passband is 0.1 dB, and the minimum attenuation αs that the stopband should reach is 80 dB).

[0037] Secondly, the filter coefficient vector A (first coefficient vector) and vector B (second coefficient vector) are finally obtained through the filter design tool in MATLAB; secondly, the differential equations used to express forward and backward filtering are designed to obtain the forward transfer differential equation y1 and the backward transfer differential equation y2, and the static pressure data is forward filtered using equation y1, the pressure signal after forward filtering is mirrored, and the flipped pressure data is backward filtered using equation 2 to obtain the final pressure data; finally, the atmospheric lift velocity solution cache is added to the pressure signal after forward and backward filtering, the atmospheric lift velocity is calculated, and the final lift velocity is obtained.

[0038] like Figure 1 As shown, the lifting speed calculation method based on front and rear phase filtering includes the following steps:

[0039] Step S1: By analyzing the static pressure in the flight data, the technical parameters of the filter are determined (the technical parameters include the passband cutoff frequency ωc, the stopband cutoff frequency ωs, the maximum attenuation allowed in the passband αc, and the minimum attenuation αs that the stopband should reach);

[0040] Step S2: According to the technical specifications of the filter in step S1, the first coefficient vector A and the second coefficient vector B of the filter are obtained by using the filter design tool in MATLAB;

[0041] Step S3: Expand the input pressure sequence (original pressure sequence) forward and backward according to the lengths of vectors A and B. Specifically, the forward expansion length is the length of the first coefficient A, and the backward expansion length is the length of the second coefficient vector B;

[0042] Forward expansion method: Use the first data in the pressure sequence to linearly expand with the second, third, ..., M+1 data to obtain the forward expanded pressure sequence. Among them, M is the forward expansion length, which is equal to the length of the filter coefficient vector A;

[0043] Backward expansion method: Use the nth data in the pressure sequence to linearly expand with the n-1th, n-2th, ..., nNth data respectively. Among them, N is the backward expansion length, which is equal to the length of the filter coefficient vector B, and n is the length of the pressure sequence;

[0044] Step S4: Perform forward filtering according to the original pressure sequence, the forward pressure sequence obtained in step S3, and the backward pressure sequence combined with the forward filtering difference equation to remove high-frequency noise or unnecessary frequency components in the signal and generate a pressure signal after forward filtering;

[0045] Step S5: Flip the pressure signal after forward filtering, that is, mirror-reverse the pressure signal (pressure signal after forward filtering) along the time axis to obtain a pressure signal with opposite time and the same frequency as the input of backward filtering;

[0046] Step S6: Combine the data obtained in step S5 with the backward filtering difference equation, perform backward filtering, remove the phase delay introduced by the forward filtering, and obtain the final pressure signal. This pressure signal (final pressure signal) is completely consistent with the original input pressure signal (pressure signal after forward filtering) in time;

[0047] Step S7: Put the final pressure signal obtained in step S6 into the atmospheric lift speed calculation buffer, calculate the pressure change rate within a fixed time Δt in the pressure buffer, and calculate the inverse of the atmospheric pressure gradient, calculate the atmospheric lift speed according to the lift speed formula, and obtain the final lift speed.

[0048] Specifically, the formula for calculating the lifting speed is as follows:

[0049]

[0050] Where: H rate is the lifting speed, in m / s;

[0051] ΔH is the change in pressure altitude within Δt time, unit: m;

[0052] is the pressure change rate within a fixed time Δt;

[0053] It is the differential of pressure altitude to static pressure, that is, the inverse of the atmospheric pressure gradient.

[0054] in, The value of is also related to the vertical temperature gradient β.

[0055] When β = 0,

[0056] When β≠0,

[0057] ΔP S —Change in static pressure within Δt time unit: kPa;

[0058] Δt——pressure buffer length*pressure sampling time (ms) / 1000 Unit: s;

[0059] Ps——static atmospheric pressure unit: kPa;

[0060] Tb——the lower boundary atmospheric temperature of the corresponding layer (as shown in Table 1) Unit: K;

[0061] β——vertical temperature gradient (as shown in Table 1) Unit: K / m;

[0062] Pb——the atmospheric pressure at the lower boundary of the corresponding layer (as shown in Table 1) Unit: kPa;

[0063] R——Special gas constant 287.05287 m2 / K·s2;

[0064] gn——standard acceleration of free fall 9.80665 m / s2.

[0065] Table 1 Atmospheric temperature and vertical temperature gradient

[0066]

[0067] At present, the static pressure data of the latest 30 to 50 cycles are used in the lifting speed solution. The lifting speed solution cycle is 20ms, and the lifting speed delay is about 600ms to 1000ms. After adopting the lifting speed solution method based on forward and backward filtering, the lifting speed delay is shortened by 100ms to 150ms, and the data stability is better than the lifting speed solution results currently used.

[0068] Beneficial effects of the embodiments of the present invention:

[0069] The method for calculating the lifting speed of forward and backward phase filtering in the embodiment of the present invention is based on the forward and backward filtering in the atmospheric lifting speed calculation, which can improve the real-time responsiveness of the atmospheric lifting speed data while ensuring the stability of the output data as much as possible; the forward and backward data sequences of the forward and backward filtering are expanded forward and backward according to the filter coefficient length to achieve zero phase delay and ensure the real-time performance of the filtering.

[0070] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other, and with each other.

Claims

1. A method for calculating lifting speed based on forward and backward phase filtering, characterized in that: include: Analyze the static pressure in the flight data to obtain a first coefficient vector and a second coefficient vector of the filter, forward-extend the original pressure sequence according to the first coefficient vector to generate a forward-extended pressure sequence, and backward-extend the original pressure sequence according to the second coefficient vector to generate a backward-extended pressure sequence; Performing forward filtering on the original pressure sequence, the forward-extended pressure sequence, and the backward-extended pressure sequence through a forward-filtering difference equation to generate a forward-filtered pressure signal; The forward-filtered pressure signal is mirror-flipped along the time axis to generate a flipped pressure signal, and the flipped pressure signal is backward-filtered by a backward-filtering differential equation to generate a final pressure signal; The atmospheric lifting velocity is resolved for the final pressure signal to obtain the atmospheric lifting velocity, and the final lifting velocity is obtained through the atmospheric lifting velocity calculation.

2. The method for calculating lifting speed based on forward and backward phase filtering according to claim 1, characterized in that: The method of forward-extending the original pressure sequence according to the first coefficient vector to generate a forward-extended pressure sequence and backward-extending the original pressure sequence according to the second coefficient vector to generate a backward-extended pressure sequence includes: Linearly expand the first data of the original pressure sequence and the second data to the M+1th data of the original pressure sequence respectively to generate a forward-expanded pressure sequence; wherein M is the length of the forward expansion and M is equal to the length of the first coefficient vector; The nth data of the original pressure sequence is linearly expanded with the n-1th data to n+Nth data of the original pressure sequence to generate a backward-extended pressure sequence; wherein N is the length of the backward expansion and N is equal to the length of the second coefficient vector, and n is the length of the original pressure sequence.

3. The method for calculating lifting speed based on forward and backward phase filtering according to claim 1, characterized in that: The atmospheric lifting velocity is resolved for the final pressure signal to obtain the atmospheric lifting velocity, including: The atmospheric lifting speed is resolved for the final pressure signal to calculate the pressure change rate within a fixed time Δt in the pressure buffer; According to the value of vertical temperature gradient β, the inverse value of atmospheric pressure gradient is calculated; The lifting velocity formula is used to calculate the atmospheric lifting velocity through the inverse of the atmospheric pressure gradient.

4. The method for calculating lifting speed based on forward and backward phase filtering according to claim 3 is characterized in that: According to the value of the vertical temperature gradient β, the inverse value of the atmospheric pressure gradient is calculated, including: When the vertical temperature gradient β = 0, the inverse value of the atmospheric pressure gradient Among them, P s is the atmospheric static pressure, T b is the atmospheric temperature at the lower boundary of the corresponding layer, g n is the standard acceleration of free fall, R is the special gas constant; When the vertical temperature gradient β≠0, the inverse value of the atmospheric pressure gradient Among them, P b is the atmospheric pressure at the lower boundary of the corresponding layer.

5. The method for calculating lifting speed based on forward and backward phase filtering according to claim 3 is characterized in that: The lifting velocity formula is used to calculate the atmospheric lifting velocity by the inverse of the atmospheric pressure gradient, including: The velocity of the atmosphere Among them, Δt is a fixed time period, ΔH is the change in pressure altitude within the Δt time period, is the inverse value of the atmospheric pressure gradient, is the pressure change rate within a fixed time Δt.

6. The method for calculating lifting speed based on forward and backward phase filtering according to claim 5, characterized in that: Fixed time period Δt = pressure buffer length * pressure sampling time / 1000.

7. The method for calculating lifting speed based on forward and backward phase filtering according to any one of claims 1 to 6, characterized in that: The static pressure in the flight data is analyzed to obtain a first coefficient vector and a second coefficient vector of the filter, including: Analyze the static pressure in the flight data to determine the technical parameters of the filter; The technical parameters of the filter are input into a filter design tool to obtain a first coefficient vector and a second coefficient vector of the filter.

8. The method for calculating lifting speed based on forward and backward phase filtering according to claim 7 is characterized in that: The technical parameters of the filter include the passband cutoff frequency ωc, the stopband cutoff frequency ωs, the maximum attenuation αc allowed in the passband and the minimum attenuation αs that the stopband should reach.

9. The method for calculating lifting speed based on forward and backward phase filtering according to claim 1, characterized in that: The final pressure signal is temporally consistent with the forward filtered pressure signal.

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