Method for monitoring early icing conditions on an aircraft based on ultrasonic pulse echo

Abstract

This invention proposes a method for monitoring early icing of aircraft based on ultrasonic pulse echo. The input parameters of this method include echo signals from ice-free structures, echo signals from iced structures, and the surface temperature of the structures. By analyzing and processing these input signals using the proposed method for early icing warning and ice thickness measurement based on ultrasonic pulse echo, early icing warning information and surface ice thickness data can be obtained, providing a basis for the activation and deactivation of the aircraft icing protection system. This invention can reduce the energy consumption of the aircraft icing protection system when removing ice from the aircraft surface, improving energy efficiency while ensuring flight safety, and has promising application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft icing protection and icing detection, and particularly relates to an aircraft early icing warning and ice thickness measurement signal processing method based on ultrasonic pulse echo. BACKGROUND

[0002] When the aircraft passes through the cloud containing supercooled water droplets, the ice layer on the windward surface gradually accumulates. During the flight of the aircraft, even if it only cruises for a short time in the common icing weather conditions, the icing on the windward surface will have a great impact on the performance of the aircraft, bring more serious safety hazards, and even cause the aircraft accident. Therefore, the aircraft needs to be equipped with an icing detection and warning device to provide the aircraft with icing warning and surface ice thickness and other icing information and start the icing protection system to avoid serious ice accumulation on the critical parts of the aircraft and thus ensure the flight safety of the aircraft. SUMMARY

[0003] The purpose of the present application is to provide an aircraft early icing warning and ice thickness measurement signal processing method based on ultrasonic pulse echo.

[0004] Technical scheme: The three input parameters of the non-icing structure echo signal, the structure icing echo signal and the structure surface temperature are analyzed and processed by the proposed aircraft early icing warning and ice thickness measurement method based on ultrasonic pulse echo, and the aircraft early icing warning information and the surface ice thickness data are obtained.

[0005] The aircraft early icing condition monitoring method based on ultrasonic pulse echo comprises:

[0006] S1: When the aircraft surface is free of ice, the original signal is acquired and preprocessed, and two time threshold A interval and B interval are set according to the ultrasonic pulse echo principle;

[0007] S2: The structure icing early warning is realized by a signal measurement algorithm;

[0008] S3: The structure surface icing thickness measurement is performed according to the ultrasonic pulse echo thickness measurement TOF method.

[0009] Further, the S1 specifically comprises:

[0010] The non-icing structure original signal is subjected to Hilbert transform to obtain the original structure signal envelope, and the structure echo peak A1 and the structure echo peak time t1 are obtained by global search in the structure signal envelope;

[0011] According to the obtained structural echo peak time t1, the signal section is further intercepted to obtain effective data P1(t), t∈(t1-T0 / 2, end), wherein T0 is a transmission pulse period, end is a data end time, and two threshold intervals A interval and B interval are set in the effective data according to an ultrasonic pulse echo principle, and are respectively used for obtaining structural echo peak value and ice layer echo peak value information in subsequent structural icing early warning and ice thickness measurement algorithms.

[0012] Further, the S2 is specifically:

[0013] S21 processes the input structural ice-free effective reference signal and structural icing effective collection signal, and extracts a judgment parameter;

[0014] S22 obtains a structural icing warning conclusion according to the judgment parameter.

[0015] Further, the S21 is specifically:

[0016] S211 performs a cross-correlation judgment on the input structural ice-free effective reference signal and structural icing effective collection signal according to to calculate a signal cross-correlation coefficient ε, wherein τ is a delay time;

[0017] S212 searches for a structural icing effective collection signal structural echo peak value A1' in a structural echo peak judgment interval gate A, and obtains a structural echo reflection coefficient r according to .

[0018] Further, according to the signal cross-correlation coefficient ε, the structural echo reflection coefficient r, and the input structural surface temperature, early icing on the structural surface is judged: when and only when the structural surface temperature T < 0 ℃, the signal cross-correlation coefficient ε < 0.85, and the structural echo reflection coefficient r < 0.7, the structural surface is determined to be iced, and a warning signal is provided; otherwise, it is considered that the structural surface is not iced, and no structural icing warning is performed.

[0019] Further, the S3 is specifically:

[0020] S31 searches for an ice layer echo peak time t2 of the structural icing effective collection signal in an ice layer echo peak information judgment threshold B interval;

[0021] S32 according to the input structural surface temperature T, performs ice layer sound speed C L low temperature correction according to formula C L .

[0022] S33 calculates the structural surface icing ice layer thickness H according to .

[0023] Beneficial effects:

[0024] Based on the technical solutions provided in the present application, early icing warning information and surface ice thickness data of an airplane can be obtained, which provides a basis for starting and stopping of an airplane icing protection system. The present application can reduce energy consumption of the airplane icing protection system in removing surface ice of the airplane, improve energy utilization rate while ensuring flight safety of the airplane, and has a promising application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 An algorithm function implementation schematic diagram is shown in the figure.

[0026] Figure 2 An original signal preprocessing example schematic diagram is shown in the figure.

[0027] Figure 3 A signal initialization processing process schematic diagram is shown in the figure.

[0028] Figure 4 An early icing warning and ice thickness data measurement algorithm schematic diagram is shown in the figure.

[0029] Figure 5 A signal cross-correlation coefficient curve diagram is shown in the figure.

[0030] Figure 6 A structure echo reflection coefficient curve diagram is shown in the figure. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation of the present application.

[0032] The present application proposes an airplane early icing condition monitoring method based on ultrasonic pulse echo, input parameters of the method include ice-free structure echo signal, structure icing echo signal and structure surface temperature, analysis and processing of the above input signals are performed by using the proposed airplane early icing warning and ice thickness measurement method based on ultrasonic pulse echo, and an algorithm function implementation schematic of early icing warning information and surface ice thickness data of the airplane is shown as follows Figure 1 .

[0033] The present application is an airplane early icing condition monitoring method based on ultrasonic pulse echo, the method comprises:

[0034] S1: original signal acquisition and preprocessing are performed when the airplane surface is ice-free, two time threshold A interval and B interval are set according to the ultrasonic pulse echo principle;

[0035] S2: early icing warning of the structure is realized by a signal measurement algorithm.

[0036] S3 carries out ice thickness measurement on the structure surface icing according to the ultrasonic pulse echo thickness TOF method.

[0037] The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm.

[0038] The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm. Figure 2 The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm. Figure 3 The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm. The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm.

[0039] Firstly, the Hilbert transform is performed on the original ice-free structure signal to obtain the original signal envelope P1(t), t∈(0, end).

[0040] Then, the transmission pulse part in the signal is removed to obtain the structure signal envelope P1(t), t∈(T0, end), and global search is performed in the structure signal envelope to obtain the structure echo peak A1 and the structure echo peak time t1.

[0041] Finally, the signal interval is further intercepted according to the obtained structure echo peak time t1 to obtain the effective data P1(t), t∈(t1-T0 / 2, end), and two data judgment intervals A gate and B gate are set in the effective data according to the ultrasonic pulse echo principle, which are respectively used for subsequent structure icing early warning and ice thickness measurement algorithm to obtain the structure echo peak and ice layer echo peak information.

[0042] The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm. Figure 4 The signal processing method comprises a signal initialization algorithm and a signal measurement algorithm.

[0043] Firstly, the structure surface icing early warning judgment is performed. The implementation of the structure icing early warning effect needs to evaluate the three judgment parameters of the signal cross-correlation coefficient, the structure echo reflection coefficient and the structure surface temperature. Therefore, the input structure ice-free effective reference signal and the structure icing effective acquisition signal are processed to extract the judgment parameters:

[0044] (1) The input structure ice-free effective reference signal and the structure icing effective acquisition signal are cross-correlated according to the formula in the figure, and the signal cross-correlation coefficient ε is calculated.

[0045] (2) The structure echo peak A1' of the structure icing effective acquisition signal is searched in the structure echo peak judgment interval gate A, and the structure echo reflection coefficient r is calculated according to the formula in the figure.

[0046] Combined with the signal cross-correlation coefficient obtained by the above analysis processing, the structure echo reflection coefficient and the input structure surface temperature, the early icing of the structure surface can be early warned and judged: when and only when the structure surface temperature T < 0℃, the signal cross-correlation coefficient ε < 0.85 and the structure echo reflection coefficient r < 0.7, the structure surface icing is determined, and a warning signal is provided; otherwise, it is considered that the structure surface is not iced, and the structure icing early warning is not performed.

[0047] The setting basis of the three judgment parameter threshold values is: the freezing point of water under normal pressure is T = 0℃, and icing phenomenon may occur only when the temperature is lower than the freezing point; the signal cross-correlation coefficient is set to judge the existence of the attached matter on the structure surface, when the structure surface has the attached matter (water or ice), under each frequency pulse signal, the cross-correlation coefficient of the attached matter growth stage under different attached matter thicknesses is less than 0.85, as shown in the following figure; the structure echo reflection coefficient is set to distinguish the attached matter types on the structure surface, when the attached matter is ice, the structure echo reflection coefficient under different attached matter thicknesses is less than 0.7, as shown in the following figure. Figure 5 、 Figure 6

[0048] Next, the structure icing thickness data acquisition is performed. After the early icing of the structure surface is determined and early warned, the structure surface icing thickness measurement can be realized according to the ultrasonic pulse echo thickness TOF method, and the specific process is as follows:

[0049] (1) the ice layer echo peak time t2 of the structure icing effective acquisition signal is searched in the ice layer echo peak information judgment interval gate B;

[0050] (2) according to the input structure surface temperature T, the ice layer sound speed is corrected at low temperature according to the formula in the figure, so as to obtain more accurate ice thickness measurement results

[0051] (3) the structure surface icing ice layer thickness H is calculated according to the formula in the figure.

[0052] Thus, the early warning and ice thickness measurement process of the structure icing are completed.

[0053] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.​

Claims

1. A method for monitoring the early icing conditions of an aircraft based on ultrasonic pulse-echo, characterized in that, The method comprises: S1, original signal acquisition and preprocessing are performed when the aircraft surface is ice-free, and two time threshold intervals A and B are set according to the ultrasonic pulse echo principle; S2, early warning of structure icing is realized through a signal measurement algorithm; the S2 specifically comprises: S21, input structure ice-free effective reference signals and structure icing effective acquisition signals are processed, and a judgment parameter is extracted; the S21 specifically comprises: S211 according to the input structure ice effective reference signal and structure ice effective acquisition signal basis correlation judgment is carried out, and a signal cross-correlation coefficient ε is calculated, wherein τ is a delay time; S212 retrieves the structure echo peak value A1' of the structure icing effective collection signal in the structure echo peak value judgment interval gate A, and calculates the structure echo reflection coefficient r according to the structure echo peak value A1' and the structure echo peak value A1. S22, a conclusion of structure icing early warning is obtained according to the judgment parameter; early icing of the structure surface is judged according to a signal cross-correlation coefficient epsilon, a structure echo reflection coefficient r and input structure surface temperature; when and only when the structure surface temperature T is less than 0 DEG C, the signal cross-correlation coefficient epsilon is less than 0.85 and the structure echo reflection coefficient r is less than 0.7, the structure surface is determined to be iced, and a warning signal is provided; otherwise, it is considered that the structure surface is ice-free, and no structure icing early warning is performed; S3, structure surface icing thickness measurement is performed according to the ultrasonic pulse echo thickness TOF method.

2. The ultrasonic pulse-echo based method of monitoring early icing conditions on an aircraft as defined in claim 1, wherein, The S1 specifically comprises: Hilbert transform is performed on the original ice-free structure signal to obtain an original structure signal envelope, and global search is performed on the structure signal envelope to obtain a structure echo peak A1 and a structure echo peak time t1; effective data P1(t) is obtained by further intercepting the signal interval according to the obtained structure echo peak time t1, t is an element of (t1-T0 / 2, end), wherein T0 is a transmission pulse period, end is the end time of data, and two threshold interval A and B are set in the effective data according to the ultrasonic pulse echo principle, which are respectively used for obtaining structure echo peak and ice layer echo peak information in subsequent structure icing early warning and ice thickness measurement algorithms.

3. The ultrasonic pulse-echo based method of monitoring incipient icing conditions on an aircraft as defined in claim 1, wherein, The S3 specifically comprises: S31, the ice layer echo peak time t2 of the structure icing effective acquisition signal is searched in the ice layer echo peak information judgment threshold interval B. S32 The ice layer sound velocity C is calculated according to the input structure surface temperature T in accordance with the formula C = 3837.9 - 2.812 · T L S32 The ice layer sound velocity C is calculated according to the input structure surface temperature T in accordance with the formula C = 3837.9 - 2.812 · T L Temperature correction at low temperatures; S33 depends on The ice thickness H of the icing structure surface is calculated.

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